T helper 17 cells in airway diseases: from laboratory bench to bedside

Calprotectin is regulated by IL-17A and induces steroid hyporesponsiveness in asthma

BACKGROUND

Calprotectin, a calcium-binding protein, plays a crucial role in inflammation and has been associated with various inflammatory diseases, including asthma. However, its regulation and impact on steroid hyporesponsiveness, especially in severe asthma, remain poorly understood.

METHODS

This study investigated the regulation of calprotectin proteins (S100A8 and S100A9) by IL-17 and its role in steroid hyporesponsiveness using in vitro and in vivo models. Calprotectin expression was assessed in primary bronchial fibroblasts from healthy controls and severe asthmatic patients, as well as in mouse models of steroid hyporesponsive lung inflammation induced by house dust mite (HDM) allergen and cyclic-di-GMP (cdiGMP) adjuvant. The effects of IL-17A stimulation on calprotectin expression and steroid response markers in bronchial epithelial and fibroblast cells were examined. Additionally, the therapeutic potential of paquinimod, a calprotectin inhibitor, in mitigating airway inflammation and restoring steroid response signatures in the mouse model was evaluated.

RESULTS

The results demonstrated upregulation of calprotectin expression in asthmatic bronchial fibroblasts compared to healthy controls, as well as in refractory asthma samples compared to non-refractory asthma. IL-17 stimulation induced calprotectin expression and dysregulated glucocorticoid response signatures in lung epithelial and fibroblast cells. Treatment with paquinimod reversed IL-17-induced dysregulation of steroid signatures, indicating the involvement of calprotectin in this process. In the HDM/cdiGMP mouse model, paquinimod significantly attenuated airway inflammation and hyperresponsiveness, and restored steroid response signatures, whereas dexamethasone showed limited efficacy. Mechanistically, paquinimod inhibited MAPK/ERK and NF-κB pathways downstream of calprotectin, leading to reduced lung inflammation.

CONCLUSION

These findings highlight calprotectin as a potential therapeutic target regulated by IL-17 in steroid hyporesponsive asthma. Targeting calprotectin may offer a promising approach to alleviate airway inflammation and restore steroid responsiveness in severe asthma. Further investigations are warranted to explore its therapeutic potential in clinical settings and elucidate its broader implications in steroid mechanisms of action.

Precision medicine for severe asthma - Biological targeted therapy

Severe asthma is a complex and heterogeneous chronic airway inflammatory disease. Current treatment strategies are increasingly focused on disease classification, facilitating the transition towards personalized medicine by integrating biomarkers and monoclonal antibodies for tailored therapeutic approaches. Several approved biological agents, including anti-immunoglobulin E (IgE), anti-interleukin (IL)-4, anti-IL-5, and anti-thymic stromal lymphopoietin (TSLP) monoclonal antibodies, have demonstrated significant efficacy in reducing asthma exacerbations, eosinophil counts, improving lung function, minimizing oral corticosteroid usage, and enhancing patients' quality of life. The utilization of these biological agents has brought about profound transformations in the management of severe asthma. This article provides a comprehensive review on biomarkers and biological agents for severe asthma while emphasizing the increasing importance of further research into its pathogenesis and novel treatment modalities.

Effect of ω-9MUFAs in Fat Emulsion on Serum Interleukin-6 in Rats with Lipopolysaccharide-induced Lung Injury

AIM

This study aimed to investigate how ω-9 MUFAs in fat emulsion affect serum IL- 6 levels in rats with lipopolysaccharide (LPS)-induced lung injury.

BACKGROUND

Research suggests that acute lung injury (ALI) develops acute respiratory distress syndrome (ARDS) due to the activation of many inflammatory factors. ALI may be treated by reducing inflammation. Fat emulsion is used in parenteral nutrition for critically ill patients to regulate the body's inflammatory response. It is mostly made up of ω-9 MUFAs (Clinoleic), which can regulate the inflammatory response.

OBJECTIVE

The effect of ω-9MUFAs on the secretion of IL-6 in ALI rats was studied in order to provide a basis for the rational use of fat emulsion in clinical practice and provide new ideas for the diagnosis and treatment of ALI.

METHODS

The control, model, and -9MUFAs groups consisted of 18 female Sprageue-Dawley (SD) young rats (180 ± 20 g). The SD young rats received normal saline and were not operated. LPS-induced ALI animals received tail vein injections of normal saline. SD young rats were first triggered with acute lung injury by LPS (3 mg/kg) and then injected with 3 mg/kg of ω-9MUFAs via the tail vein. The expression levels of IL-6, an activator of signal transduction transcription 3 (STAT3), transforming growth factor-β (TGF-β), and glycoprotein 130 (GP130) in serum and lung tissues were determined by ELISA and Western blot methods.

RESULTS

Compared with the model group, the survival rate of rats in the ω-9 MUFAs group was significantly increased, and the difference was statistically significant (p<0.05). Compared with the model group, the lung pathology of rats in the ω-9 MUFAs group was significantly improved, and the expression levels of IL-6, TGF-β1, GP130, IL-1 and other proteins were significantly decreased. The difference was statistically significant (p<0.05).

CONCLUSION

In LPS-induced lung injury, ω-9MUFAs may alleviate symptoms by inhibiting the IL-6/GP130/STAT3 pathway.

Personalized Medicine in Severe Asthma: From Biomarkers to Biologics

Severe asthma is a complex and heterogeneous clinical condition presented as chronic inflammation of the airways. Conventional treatments are mainly focused on symptom control; however, there has been a shift towards personalized medicine. Identification of different phenotypes driven by complex pathobiological mechanisms (endotypes), especially those driven by type-2 (T2) inflammation, has led to improved treatment outcomes. Combining biomarkers with T2-targeting monoclonal antibodies is crucial for developing personalized treatment strategies. Several biological agents, including anti-immunoglobulin E, anti-interleukin-5, and anti-thymic stromal lymphopoietin/interleukin-4, have been approved for the treatment of severe asthma. These biological therapies have demonstrated efficacy in reducing asthma exacerbations, lowering eosinophil count, improving lung function, diminishing oral corticosteroid use, and improving the quality of life in selected patients. Severe asthma management is undergoing a profound transformation with the introduction of ongoing and future biological therapies. The availability of novel treatment options has facilitated the adoption of phenotype/endotype-specific approaches and disappearance of generic interventions. The transition towards precision medicine plays a crucial role in meticulously addressing the individual traits of asthma pathobiology. An era of tailored strategies has emerged, allowing for the successful targeting of immune-inflammatory responses that underlie uncontrolled T2-high asthma. These personalized approaches hold great promise for improving the overall efficacy and outcomes in the management of severe asthma. This article comprehensively reviews currently available biological agents and biomarkers for treating severe asthma. With the expanding repertoire of therapeutic options, it is becoming increasingly crucial to comprehend the influencing factors, understand the pathogenesis, and track treatment progress in severe asthma.

Autophagy prevents early proinflammatory responses and neutrophil recruitment during Mycobacterium tuberculosis infection without affecting pathogen burden in macrophages

The immune response to Mycobacterium tuberculosis infection determines tuberculosis disease outcomes, yet we have an incomplete understanding of what immune factors contribute to a protective immune response. Neutrophilic inflammation has been associated with poor disease prognosis in humans and in animal models during M. tuberculosis infection and, therefore, must be tightly regulated. ATG5 is an essential autophagy protein that is required in innate immune cells to control neutrophil-dominated inflammation and promote survival during M. tuberculosis infection; however, the mechanistic basis for how ATG5 regulates neutrophil recruitment is unknown. To interrogate what innate immune cells require ATG5 to control neutrophil recruitment during M. tuberculosis infection, we used different mouse strains that conditionally delete Atg5 in specific cell types. We found that ATG5 is required in CD11c+ cells (lung macrophages and dendritic cells) to control the production of proinflammatory cytokines and chemokines during M. tuberculosis infection, which would otherwise promote neutrophil recruitment. This role for ATG5 is autophagy dependent, but independent of mitophagy, LC3-associated phagocytosis, and inflammasome activation, which are the most well-characterized ways that autophagy proteins regulate inflammation. In addition to the increased proinflammatory cytokine production from macrophages during M. tuberculosis infection, loss of ATG5 in innate immune cells also results in an early induction of TH17 responses. Despite prior published in vitro cell culture experiments supporting a role for autophagy in controlling M. tuberculosis replication in macrophages, the effects of autophagy on inflammatory responses occur without changes in M. tuberculosis burden in macrophages. These findings reveal new roles for autophagy proteins in lung resident macrophages and dendritic cells that are required to suppress inflammatory responses that are associated with poor control of M. tuberculosis infection.

Saikosaponin D inhibits nasal inflammation by regulating the transcription factors T-box protein expressed in T cells/GATA-3 and retinoic acid-related orphan nuclear receptor γt in a murine model of allergic rhinitis

Context

Saikosaponin D (SSD) is a commonly prescribed agent against inflammatory diseases in Asian countries. However, the anti-allergic inflammatory effect of SSD in allergic rhinitis (AR) model is not well known.

Objective

We investigated the anti-allergic and anti-inflammatory effects of SSD on the ovalbumin (OVA)-induced AR model.

Materials and method

BALB/c mice were divided into the control, OVA, OVA + SSD, and OVA + dexamethasone (Dex) groups. AR was established by intraperitoneal injection with OVA adsorbed to aluminum hydroxide, and intranasal challenge with OVA. Thereafter, the mice were treated with 10 mg/kg BW (Body weight) of OVA + SSD and 2.5 mg/kg BW of Dex orally for 11 days before being challenged. Subsequently, the mice were challenged with OVA 1 h after SSD or Dex treatment. The Control group was treated with saline only.

Results

The addition of 10 mg/kg BW of OVA + SSD significantly ameliorated the nasal symptoms including sneezing and rubbing from 30 ± 5.2 times in OVA group to 20 ± 5.8 times. Moreover, OVA + SSD group decreased the production of TNF-α, IL-4, IL-5, IL-17, GATA-3 and RORγ about 1.2-1.4-fold compared to the OVA-induced AR mice near to 2.5 mg/kg BW of Dex levels. Meanwhile OVA + SSD group slightly increased the levels of INF-γ, IL-12 and T-bet about 1.8-2.0-fold compared to the OVA group near to control group. Notably, OVA + SSD group also reduced the levels of OVA-specific IgE and IgG1 about 0.5-2.5-fold compared OVA group but increased the levels of IgG2a in serum. The results were analyzed using Graph Pad Prism software (v5.0, La Jolla, CA, USA).

Conclusion

SSD may represent an alternative therapeutic approach for the treatment of patients with AR through the regulation of transcription factors T-bet, GATA-3, and RORγ in inflammatory cells.

Aryl Hydrocarbon Receptor Activation Ameliorates Acute Respiratory Distress Syndrome through Regulation of Th17 and Th22 Cells in the Lungs

Acute respiratory distress syndrome (ARDS) is triggered by a variety of insults, including bacterial and viral infections, and this leads to high mortality. While the role of the aryl hydrocarbon receptor (AhR) in mucosal immunity is being increasingly recognized, its function during ARDS is unclear. In the current study, we investigated the role of AhR in LPS-induced ARDS. AhR ligand, indole-3-carbinol (I3C), attenuated ARDS which was associated with a decrease in CD4+ RORγt +IL-17a+IL-22+ pathogenic Th17 cells, but not CD4+RORγt +IL-17a+IL-22- homeostatic Th 17 cells, in the lungs. AhR activation also led to a significant increase in CD4+IL-17a-IL-22+ Th22 cells. I3C-mediated Th22 cell expansion was dependent on the AhR expression on RORγt+ cells. AhR activation downregulated miR-29b-2-5p in immune cells from the lungs, which in turn downregulated RORc expression and upregulated IL-22. Collectively, the current study suggests that AhR activation can attenuate ARDS and may serve as a therapeutic modality by which to treat this complex disorder. IMPORTANCE Acute respiratory distress syndrome (ARDS) is a type of respiratory failure that is triggered by a variety of bacterial and viral infections, including the coronavirus SARS-CoV2. ARDS is associated with a hyperimmune response in the lungs that which is challenging to treat. Because of this difficulty, approximately 40% of patients with ARDS die. Thus, it is critical to understand the nature of the immune response that is functional in the lungs during ARDS as well as approaches by which to attenuate it. AhR is a transcription factor that is activated by a variety of endogenous and exogenous environmental chemicals as well as bacterial metabolites. While AhR has been shown to regulate inflammation, its role in ARDS is unclear. In the current study, we provide evidence that AhR activation can attenuate LPS-mediated ARDS through the activation of Th22 cells in the lungs, which are regulated through miR-29b-2-5p. Thus, AhR can be targeted to attenuate ARDS.

Continuous positive airway pressure therapy suppresses inflammatory cytokines and improves glucocorticoid responsiveness in patients with obstructive sleep apnea and asthma: A case-control study

CONTEXT

Asthma and obstructive sleep apnea (OSA) are prevalent respiratory disorders that frequently coexist. Continuous positive airway pressure (CPAP) therapy is the standard treatment for OSA. However, its effects on systemic inflammation and glucocorticoid responsiveness in OSA patients with asthma are largely unknown.

AIMS

To examine the potential role of CPAP therapy in reducing systemic inflammation and improving glucocorticoid responsiveness in asthmatic patients with OSA.

SETTINGS AND DESIGN

A case-control study was conducted at the respiratory and sleep clinics involving patients with OSA and patients with asthma and OSA.

METHODS

The levels of inflammatory asthma biomarkers (interleukin [IL]-4, IL-17A, IL-8, IL-2, and interferon-γ [IFN-γ]), and glucocorticoid receptors (GR)-α and GR-β, were determined to compare systemic inflammation and glucocorticoid responsiveness between pre- and post-1-month CPAP treatment in both groups.

STATISTICAL ANALYSIS

The Wilcoxon signed-rank test was used to compare inflammatory biomarkers before and after CPAP therapy. P < 0.05 considered statistically significant. The analysis was performed using SPSS.

RESULTS

Recruited patients (n = 47), 51% (n = 24) had OSA and 49% (n = 23), had OSA with asthma. Interestingly, the blood levels of IL-17 and IL-8 were significantly decreased post-CPAP therapy in OSA patients, whereas IL-4, IL-17, and IFN-γ were significantly reduced post-CPAP treatment in OSA patients with asthma. Remarkably, CPAP therapy improved glucocorticoid responsiveness in asthmatic patients with OSA, but not in the OSA group and an increase in the GR-α/GR-β ratio was noted post-CPAP therapy.

CONCLUSIONS

Continuous positive airway pressure therapy improved responsiveness to glucocorticoid treatment and demonstrated a suppressive effect on proinflammatory cytokines in asthmatics with OSA.

Gene polymorphisms in asthma: a narrative review

Background and Objective

Asthma is a heterogeneous disease caused by interactions between genetic and environmental factors. Genome-wide association studies (GWAS) have revealed that genetic variation plays a crucial role in the occurrence and development of asthma. The objective is to systematically review the existing literature on the association between gene polymorphisms and asthma to better understand the relationship between genetic factors and the occurrence and development of asthma.

Methods

We used keywords "asthma" and "gene polymorphism" with their combinations to search for relevant literature published from 2000 to 2021 in the PubMed database and the foreign medical literature retrieval service (FMRS). All articles included in the review are English. Then, we summarized the information pertaining to the genetic factors related to asthma susceptibility.

Key Content and Findings

This study summarized the information on 10 gene variants related to the risk of asthma published over the past 20 years, which will assist in further understanding the role of genetic variants in the risk of asthma.

Conclusion

Dozens of candidate genes have been identified that were associated with asthma risk. Asthmatics existed specific gene variation performed different response to therapy. Personalized therapy based on genotypic profiling would be an important direction in the future. However, it remains a great challenge for us to explore the relationship between gene polymorphisms and pathophysiological mechanism of asthma.

Characteristics, phenotypes, mechanisms and management of severe asthma

ABSTRACT

Severe asthma is "asthma which requires treatment with high dose inhaled corticosteroids (ICS) plus a second controller (and/or systemic corticosteroids) to prevent it from becoming 'uncontrolled' or which remains 'uncontrolled' despite this therapy." The state of control was defined by symptoms, exacerbations and the degree of airflow obstruction. Therefore, for the diagnosis of severe asthma, it is important to have evidence for a diagnosis of asthma with an assessment of its severity, followed by a review of comorbidities, risk factors, triggers and an assessment of whether treatment is commensurate with severity, whether the prescribed treatments have been adhered to and whether inhaled therapy has been properly administered. Phenotyping of severe asthma has been introduced with the definition of a severe eosinophilic asthma phenotype characterized by recurrent exacerbations despite being on high dose ICS and sometimes oral corticosteroids, with a high blood eosinophil count and a raised level of nitric oxide in exhaled breath. This phenotype has been associated with a Type-2 (T2) inflammatory profile with expression of interleukin (IL)-4, IL-5, and IL-13. Molecular phenotyping has also revealed non-T2 inflammatory phenotypes such as Type-1 or Type-17 driven phenotypes. Antibody treatments targeted at the T2 targets such as anti-IL5, anti-IL5Rα, and anti-IL4Rα antibodies are now available for treating severe eosinophilic asthma, in addition to anti-immunoglobulin E antibody for severe allergic asthma. No targeted treatments are currently available for non-T2 inflammatory phenotypes. Long-term azithromycin and bronchial thermoplasty may be considered. The future lies with molecular phenotyping of the airway inflammatory process to refine asthma endotypes for precision medicine.

Novel Biological Therapies for Severe Asthma Endotypes

Severe asthma comprises several heterogeneous phenotypes, underpinned by complex pathomechanisms known as endotypes. The latter are driven by intercellular networks mediated by molecular components which can be targeted by specific monoclonal antibodies. With regard to the biological treatments of either allergic or non-allergic eosinophilic type 2 asthma, currently available antibodies are directed against immunoglobulins E (IgE), interleukin-5 (IL-5) and its receptor, the receptors of interleukins-4 (IL-4) and 13 (IL-13), as well as thymic stromal lymphopoietin (TSLP) and other alarmins. Among these therapeutic strategies, the best choice should be made according to the phenotypic/endotypic features of each patient with severe asthma, who can thus respond with significant clinical and functional improvements. Conversely, very poor options so far characterize the experimental pipelines referring to the perspective biological management of non-type 2 severe asthma, which thereby needs to be the focus of future thorough research.

Endotypes of chronic rhinosinusitis: Relationships to disease phenotypes, pathogenesis, clinical findings, and treatment approaches

Chronic rhinosinusitis (CRS) is a common clinical syndrome that produces significant morbidity and costs to our health system. The study of CRS has progressed from an era focused on phenotype to include endotype-based information. Phenotypic classification has identified clinical heterogeneity in CRS based on endoscopically observed features such as presence of nasal polyps, presence of comorbid or systemic diseases, and timing of disease onset. More recently, laboratory-based findings have established CRS endotype based upon specific mechanisms or molecular biomarkers. Understanding the basis of widespread heterogeneity in the manifestations of CRS is advanced by findings that the three main endotypes, Type 1, 2, and 3, orchestrate the expression of three distinct large sets of genes. The development and use of improved methods of endotyping disease in the clinic are ushering in an expansion of the use of biological therapies targeting Type 2 inflammation now and perhaps other inflammatory endotypes in the near future. The purpose of this review is to discuss the phenotypic and endotypic heterogeneity of CRS from the perspective of advancing the understanding of the pathogenesis and improvement of treatment approaches and outcomes.

Isoforskolin Alleviates AECOPD by Improving Pulmonary Function and Attenuating Inflammation Which Involves Downregulation of Th17/IL-17A and NF-κB/NLRP3

Chronic obstructive pulmonary disease (COPD), a major cause of morbidity and mortality worldwide, is widely considered to be related to cigarette smoke (CS), and viral infections trigger acute exacerbation of COPD (AECOPD). Isoforskolin (ISOF) is a bioactive component from the plant Coleus forskohlii, native to Yunnan in China. It has been demonstrated that ISOF has anti-inflammatory effect on acute lung injury animal models. In the present study, we investigated the efficacy and mechanism of ISOF for the prevention and treatment of AECOPD. Mice were exposed to CS for 18 weeks and then infected with influenza virus A/Puerto Rico/8/34 (H1N1). ISOF (0.5, 2 mg/kg) was intragastrically administered once a day after 8 weeks of exposure to cigarette smoke when the body weight and lung function of model mice declined significantly. The viral load, pulmonary function, lung morphology, Th17 cells, and inflammatory cytokines in lung tissues were evaluated. The expression of nuclear factor κB (NF-κB) and NOD-like receptor pyrin domain–containing protein 3 (NLRP3) inflammasome pathways were detected. The results showed that ISOF treatment reduced the viral load in the lung homogenate, decreased the lung index of model mice, and lung pathological injuries were alleviated. ISOF also improved the pulmonary function with increased FEV0.1/FVC and decreased Rn and Rrs. The levels of inflammatory mediators (TNF-α, IL-1β, IL-6, IL-17A, MCP-1, MIG, IP-10, and CRP) in the lung homogenate were reduced after ISOF treatment. ISOF decreased the proportion of Th17 cells in the lung tissues by the flow cytometry test, and the protein expression levels of RORγt and p-STAT3 were also decreased. Furthermore, ISOF significantly inhibited the activation of NF-κB signaling and NLRP3 inflammasome in the lung tissues of model mice. In conclusion, ISOF alleviates AECOPD by improving pulmonary function and attenuating inflammation via the downregulation of proinflammatory cytokines, Th17/IL-17 A, and NF-κB/NLRP3 pathways.

Asthma Phenotypes as a Guide for Current and Future Biologic Therapies

Asthma has been increasingly recognized as being a heterogeneous disease with multiple distinct mechanisms and pathophysiologies. Evidence continues to build regarding the existence of different cell types, environmental exposures, pathogens, and other factors that produce a similar set of symptoms known collectively as asthma. This has led to a movement from a "one size fits all" symptom-based methodology to a more patient-centered, individualized approach to asthma treatment targeting the underlying disease process. A significant contributor to this shift to more personalized asthma therapy has been the increasing availability of numerous biologic therapies in recent years, providing the opportunity for more targeted treatments. When targeted biologics began to be developed for treatment of asthma, the hope was that distinct biomarkers would become available, allowing the clinician to determine which biologic therapy was best suited for which patients. Presence of certain biomarkers, like eosinophilia or antigen-specific IgE, is important features of specific asthma phenotypes. Currently available biomarkers can help with decision making about biologics, but are generally too broad and non-specific to clearly identify an asthma phenotype or the single biologic best suited to an asthmatic. Identification of further biomarkers is the subject of intense research. Yet, identifying a patient's asthma phenotype can help in predicting disease course, response to treatment, and biologic therapies to consider. In this review, major asthma phenotypes are reviewed, and the evidence for the utility of various biologics, both those currently on the market and those in the development process, in each of these phenotypes is explored.

Andrographolide Inhibition of Th17-Regulated Cytokines and JAK1/STAT3 Signaling in OVA-Stimulated Asthma in Mice

Asthma has long been considered a disease of airway inflammation. The excessive or prolonged production of inflammatory mediators can result in airway remodeling and severe clinical syndromes such as dyspnea or even apnea. Therefore, pharmaceutical intervention is required to restrain the excessive release of such inflammatory mediators in control of asthma. Novel therapeutics and mechanistic insight are sought for the management of this chronic inflammatory disease. Andrographolide (AG) is a type of diterpenoid ester compound and is reported to demonstrate multiple properties such as antioxidation and anti-inflammation. However, the anti-inflammatory capacity of AG by regulating immunologic function in airway of asthma has not been fully studied to date. Therefore, this study investigates whether AG is capable of suppressing the inflammatory response of asthma in OVA-stimulated mice and the mechanism by which this is achieved. Animals were randomly divided into 4 groups: control group, OVA model group, OVA + AG (0.1 mg/ml) group, and OVA + dimethylsulfoxide (DMSO) group. The serum, BALF, and lung tissue of the mice were collected separately for the administration of ELISA, rt-PCR, western blot and pathological section and staining. We found that AG attenuated the OVA-induced production of IL-6, IL-17A, IL-17F, and RORγt; inhibited the OVA-mediated phosphorylation of JAK 1 and STAT3; and alleviated airway remodeling and the neutrophil infiltration of lung tissue. We conclude that AG inhibits the inflammatory response of asthma in OVA-stimulated mice by blocking the activation of Th17-regulated cytokines and the JAK1/STAT3 signaling pathway.

Biologics in severe asthma

Asthma is a chronic airway disease consisting of usually variable airflow limitation and bronchial hyperresponsiveness. Many different phenotypes characterize the clinical expression of asthma, determined by heterogeneous inflammatory patterns driven by distinct cellular and molecular mechanisms known as endotypes. Inside the complex framework of asthma pathobiology, several molecules such as immunoglobulins E (IgE), pro-inflammatory cytokines and their receptors can be targeted by present and future biological treatments of severe asthma. Within this context, already registered monoclonal antibodies including omalizumab, mepolizumab, reslizumab, benralizumab and dupilumab may interfere at various levels with the pathogenic pathways responsible for type-2 airway inflammation. In particular, these drugs target IgE (omalizumab), IL-5 (mepolizumab and reslizumab), IL-5 receptor (benralizumab) and IL-4/IL-13 receptors (dupilumab), respectively. Moreover, other biological therapies are under evaluation in pre-marketing trials, mainly aimed to assess the efficacy and safety of monoclonal antibodies directed against innate cytokines such as IL-33 and thymic stromal lymphopoietin (TSLP). Among current and perspective therapeutic approaches, clinicians can choose phenotype/endotype-driven tailored treatments, able to pursue an effective control of difficult to treat type-2 asthma.

Molecular Targets for Biological Therapies of Severe Asthma

Asthma is a heterogeneous respiratory disease characterized by usually reversible bronchial obstruction, which is clinically expressed by different phenotypes driven by complex pathobiological mechanisms (endotypes). Within this context, during the last years several molecular effectors and signalling pathways have emerged as suitable targets for biological therapies of severe asthma, refractory to standard treatments. Indeed, various therapeutic antibodies currently allow to intercept at different levels the chain of pathogenic events leading to type 2 (T2) airway inflammation. In addition to pro-allergic immunoglobulin E (IgE), that chronologically represents the first molecule against which an anti-asthma monoclonal antibody (omalizumab) was developed, today other targets are successfully exploited by biological treatments of severe asthma. In particular, pro-eosinophilic interleukin 5 (IL-5) can be targeted by mepolizumab or reslizumab, whereas benralizumab is a selective blocker of IL-5 receptor. Moreover, dupilumab behaves as a dual receptor antagonist of pleiotropic interleukins 4 (IL-4) and 13 (IL-13). Besides these drugs that are already available in medical practice, other biologics are under clinical development such as those targeting innate cytokines, also including the alarmin thymic stromal lymphopoietin (TSLP), which plays a key role in the pathogenesis of type 2 asthma. Therefore, ongoing and future biological therapies are significantly changing the global scenario of severe asthma management. These new therapeutic options make it possible to implement phenotype/endotype-specific treatments, that are delineating personalized approaches precisely addressing the individual traits of asthma pathobiology. Such tailored strategies are thus allowing to successfully target the immune-inflammatory responses underlying uncontrolled T2-high asthma.

New perspectives in bronchial asthma: pathological, immunological alterations, biological targets, and pharmacotherapy

Asthma is the most common, long-lasting inflammatory airway disease that affects more than 10% of the world population. It is characterized by bronchial narrowing, airway hyperresponsiveness, vasodilatation, airway edema, and stimulation of sensory nerve endings that lead to recurring events of breathlessness, wheezing, chest tightness, and coughing. It is the main reason for global morbidity and occurs as a result of the weakening of the immune system in response to exposure to allergens or environmental exposure. In asthma condition, it results in the activation of numerous inflammatory cells like the mast and dendritic cells along with the accumulation of activated eosinophils and lymphocytes at the inflammation site. The structural cells such as airway epithelial cells and smooth muscle cells release inflammatory mediators that promote the bronchial inflammation. Long-lasting bronchial inflammation can cause pathological alterations, viz. the improved thickness of the bronchial epithelium and friability of airway epithelial cells, epithelium fibrosis, hyperplasia, and hypertrophy of airway smooth muscle, angiogenesis, and mucus gland hyperplasia. The stimulation of bronchial epithelial cell would result in the release of inflammatory cytokines and chemokines that attract inflammatory cells into bronchial airways and plays an important role in asthma. Asthma patients who do not respond to marketed antiasthmatic drugs needed novel biological medications to regulate the asthmatic situation. The present review enumerates various types of asthma, etiological factors, and in vivo animal models for the induction of asthma. The underlying pathological, immunological mechanism of action, the role of inflammatory mediators, the effect of inflammation on the bronchial airways, newer treatment approaches, and novel biological targets of asthma have been discussed in this review.

CCL20 Signaling in the Tumor Microenvironment

CCL20, as a chemokine, plays an important role in rheumatoid arthritis, psoriasis, and other diseases by binding to its receptor CCR6. Recent 10 years' research has demonstrated that CCL20 also contributes to the progression of many cancers, such as liver cancer, colon cancer, breast cancer, pancreatic cancer, and gastric cancer. This article reviews and discusses the previous studies on CCL20 roles in cancers from the aspects of its specific effects on various cancers, its remodeling on tumor microenvironment (TME), its synergistic effects with other cytokines in tumor microenvironment, and the specific mechanisms of CCL20 signal activation, illustrating CCL20 signaling in TME from multiple directions.

TNF-TNFR2 Signaling Inhibits Th2 and Th17 Polarization and Alleviates Allergic Airway Inflammation

BACKGROUND

TNF-TNFR2 signaling has been indicated to be involved in CD4+ T lymphocyte differentiation. However, its role in allergic airway inflammation is not well understood.

OBJECTIVES

The aim of this study was to investigate the role of TNF-TNFR2 signaling in allergic airway inflammation.

METHODS AND RESULTS

In this study, we used an allergen-induced asthma model to show that TNF-TNFR2 signaling alleviated allergic airway inflammation by reducing the airway infiltration of eosinophils and neutrophils. Activated TNF-TNFR2 signaling decreased the expression of Th2 and Th17 cytokines in serum and bronchoalveolar lavage fluid. Furthermore, TNF-TNFR2 signaling inhibited Th2 and Th17 polarization but promoted Th1 and CD4+CD25+ T cell differentiation in vivo.

CONCLUSIONS

Our study indicates that TNF-TNFR2 signaling alleviates allergic airway inflammation through inhibition of Th2 and Th17 cell differentiation.

Interleukin-Mediated Pendrin Transcriptional Regulation in Airway and Esophageal Epithelia

Pendrin (SLC26A4), a Cl⁻/anion exchanger, is expressed at high levels in kidney, thyroid, and inner ear epithelia, where it has an essential role in bicarbonate secretion/chloride reabsorption, iodide accumulation, and endolymph ion balance, respectively. Pendrin is expressed at lower levels in other tissues, such as airways and esophageal epithelia, where it is transcriptionally regulated by the inflammatory cytokines interleukin (IL)-4 and IL-13 through a signal transducer and activator of transcription 6 (STAT6)-mediated pathway. In the airway epithelium, increased pendrin expression during inflammatory diseases leads to imbalances in airway surface liquid thickness and mucin release, while, in the esophageal epithelium, dysregulated pendrin expression is supposed to impact the intracellular pH regulation system. In this review, we discuss some of the recent findings on interleukin-mediated transcriptional regulation of pendrin and how this dysregulation impacts airway and esophagus epithelial homeostasis during inflammatory diseases.

Fennel main constituent, trans‑anethole treatment against LPS‑induced acute lung injury by regulation of Th17/Treg function

Fennel, commonly used in traditional Chinese medicine, is known as Foeniculum vulgare Mill. And its clinical application has been shown to target many biological systems including gastroenterology, endocrinology, gynecology and respiratory. The main constituent of the fennel essential oil is trans-anethole, which has been described to have anti-inflammatory and antibacterial activities. The aim of the present study was to define the anti-inflammatory influence in acute lung injury (ALI)-bearing mice. For 3 days, ALI-bearing mice were induced by lipopolysaccharide (LPS) suspension in normal saline (24 mg/kg). On the fourth day, the trans-anethole was administrated (36.4, 72.8 or 145.6 mg/kg) as well as dexamethasone (5 mg/kg) once per day for 7 consecutive days in mice. Following the completion of drug administration mice were sacrificed. Hematoxylin and eosin staining was performed in the lung paraffin section, for comparisons between monocyte and eosinophil cells in bronchoalveolar lavage fluid. The relative gene expression of interleukin (IL)-10 and IL-17 was determined by reverse transcription-quantitative polymerase chain reaction. These two cytokines and the proportion of T helper 17 (Th17) cells and T regulatory (Treg) cells were determined by flow cytometry. The main constituent of fennel, trans-anethole, eliminated LPS-induced histopathological changes, decreased the number of inflammatory cells and resulted in a notable reduction in IL-17 mRNA expression. In addition, trans-anethole increased IL-10 mRNA expression in isolated lung tissues and resulted in a marked elevation in Treg cells and reduction in Th17 cells in spleen tissues. The results of the present study indicated that the main constituent of fennel, trans-anethole may be an anti-inflammation component, which influenced the regulation of Th17/Treg responses. Therefore, this medicinal herb may support a healing effect on diseases of inflammatory.

[Correlations between Ape1/Ref-1, ICAM-1 and IL-17A Levels in Serum and Radiation Pneumonitis for Local Advanced Non-small Cell Lung Cancer Patients]

BACKGROUND

The main manifestations of radiation pneumonitis are injury of alveolar epithelial and endothelial cells, abnormal expression of cytokines, abnormal proliferation of fibroblasts and synthesis of fibrous matrix. The occurrence of radiation pneumonitis is associated with multiplecytokine level abnormality. These cytokines can also be used as bio-markers to predict the occurrence of radiation pneumonitis. This study was to evaluate the correlation between the change of apurinic/apyrimidinic endonuclease 1/redox factor-1 (Ape1/Ref-1), intercellular adhesion molecules 1 (ICAM-1) and interleukin-17A (IL-17A) before and after radiotherapy and radiation pneumonitis for local advanced non-small cell lung cancer (NSCLC) patients with concurrent chemoradiotherapy.

METHODS

NSCLC patients (68 cases) were treated with concurrent radiotherapy and chemotherapy, every patient's normal tissue were controlled with a same radation dose. 68 local advanced NSCLC patients with concurrent chemoradiotherapy were detected the levels of Ape1/Ref-1, ICAM-1 and IL-17A in serum by ELISA before radiotherapy and in the 14th week after radiotherapy. Acute and advanced radiation pulmonary injury was graded according to Radiation Therapy Oncology Group/European Organization For Research and Treatment (RTOG/EORTC) diagnostic and grading criteria. Grade 2 or more radiation pneumonitis was taken as the main end point.

RESULTS

Eighteen cases out of 68 developed radiation pneumonitis, 50 of 68 cases have no radiation pneumonia development. There was no significant change of Ape1/Ref-1 levels before and after radiotherapy in radiation pneumonitis group (P>0.05). There was no significant change of Ape1/Ref-1 concentration in serum after radiotherapy between radiation pneumonitis group and non-radiation pneumonitis group (P>0.05). Compared with before radiotherapy, upregulation degree of ICAM-1 levels in radiation pneumonitis group was significantly higher than that in non- radiation pneumonitis group (P<0.05). There was no significant change of IL-17A concentration before and after radiotherapy in radiation pneumonitis group, but after radiotherapy IL-17A concentration in serum were remarkably higher than that in non-radiation pneumonitis group (P<0.05). Correlation analysis found that the change of ICAM-1 before and after radiotherapy has no obvious correlation with the incidence of radiation pneumonitis, and IL-17A change has obvious correlation with the incidence of radiation pneumonitis.

CONCLUSIONS

On the basis of strictly controlling radiation dose on normal tissue, IL-17A in serum could be the predictive factors of radiation pneumonitis for local advanced NSCLC patients with concurrent chemoradiotherapy.

Restoring Th17/Treg balance via modulation of STAT3 and STAT5 activation contributes to the amelioration of chronic obstructive pulmonary disease by Bufei Yishen formula

ETHNOPHARMACOLOGY RELEVANCE

Bufei Yishen formula (BYF), a Traditional Chinese Medicine (TCM), has been extensively applied in clinical treatment of chronic obstructive pulmonary disease (COPD) and provides an effective treatment strategy for the syndrome of lung-kidney qi deficiency in COPD patients. Here, we investigated its anti-COPD mechanism in COPD rats in relation to the balance between T helper (Th) 17 cells and regulatory T (Treg) cells.

METHODS

Rat model of cigarette smoke- and bacterial infection-induced COPD was established, and orally treated with BYF for 12 consecutive weeks. Then, the rats were sacrificed, their lung tissues were removed for histological analysis, and spleens and mesenteric lymph nodes (MLNs) were collected to evaluate the Th17 and Treg cells.

RESULTS

Oral treatment of BYF markedly suppressed the disease progression and alleviated the pathological changes of COPD. It also decreased the bronchoalveolar lavage fluid (BALF) levels of pro-inflammatory cytokines, including IL-1β, IL-6, TNF-α and Th17-related IL-17A, and induced a significant increase in Treg-related IL-10. Furthermore, BYF treatment obviously decreased the proportion of CD4⁺RORγt⁺ T (Th17) cell and increased the proportion of CD4⁺CD25⁺Foxp3⁺ T (Treg) cell, leading to restore the Th17/Treg balance. BYF treated groups also decreased RORγt and increased Foxp3 expression in the spleens and MLNs. BYF further inhibited the phosphorylation of signal transducer and activator of transcription-3 (STAT3) and boosted the phosphorylation of STAT5, that were critical transcription factors for TH17 and Treg differentiation.

CONCLUSION

these results demonstrated that BYF exerted its anti-COPD efficacy by restoring Th17/Treg balance via reciprocally modulating the activities of STAT3 and STAT5 in COPD rats, which may help to elucidate the underlying immunomodulatory mode of BYF on COPD treatment.

Targeted Therapy for Severe Asthma: Identifying the Right Patients

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

The Significance of Hypothiocyanite Production via the Pendrin/DUOX/Peroxidase Pathway in the Pathogenesis of Asthma

Inhaled corticosteroids (ICSs) are used as first-line drugs for asthma, and various novel antiasthma drugs targeting type 2 immune mediators are now under development. However, molecularly targeted drugs are expensive, creating an economic burden on patients. We and others previously found pendrin/SLC26A4 as a downstream molecule of IL-13, a signature type 2 cytokine critical for asthma, and showed its significance in the pathogenesis of asthma using model mice. However, the molecular mechanism of how pendrin causes airway inflammation remained elusive. We have recently demonstrated that hypothiocyanite (OSCN⁻) produced by the pendrin/DUOX/peroxidase pathway has the potential to cause airway inflammation. Pendrin transports thiocyanate (SCN⁻) into pulmonary lumens at the apical side. Peroxidases catalyze SCN⁻ and H₂O₂ generated by DUOX into OSCN⁻. Low doses of OSCN⁻ activate NF-κB in airway epithelial cells, whereas OSCN⁻ in high doses causes necrosis of the cells, inducing the release of IL-33 and accelerating inflammation. OSCN⁻ production is augmented in asthma model mice and possibly in some asthma patients. Heme peroxidase inhibitors, widely used as antithyroid agents, diminish asthma-like phenotypes in mice, indicating the significance of this pathway. These findings suggest the possibility of repositioning antithyroid agents as antiasthma drugs.

Mouse Model of IL-17-Dominant Rhinitis Using Polyinosinic-Polycytidylic Acid

Interleukin (IL)-17 plays an important role in rhinitis and the level thereof correlates with the severity of disease. However, no mouse model for IL-17-dominant rhinitis has yet been developed. Our objective was to establish a mouse model of IL-17-dominant rhinitis via intranasal application of polyinosinic-polycytidylic acid (abbreviated as Poly(I:C)). Mice were divided into 6 groups (n=8 for each group); 1) 1 negative control group, 2) 1 positive control group (OVA/alum model), 3) 2 Poly(I:C) groups (10 or 100 μg), and 4) 2 OVA/Poly(I:C) groups (10 or 100 μg). The positive control group was treated with the conventional OVA/alum protocol. In the Poly(I:C) and OVA/Poly(I:C) groups, phosphate-buffered saline or an OVA solution plus Poly(I:C) were administered. The OVA/Poly(I:C) groups exhibited significantly greater neutrophil infiltration and increased IL-17/interferon γ expression compared with the other groups. However, the levels of total immunoglobulin E (IgE), OVA-specific IgE, eosinophil infiltration, IL-4, IL-5, IL-6, and IL-10 were significantly lower in the OVA/Poly(I:C) groups than in mice subjected to conventional Th2-dominant OVA/alum treatment (the positive control group). IL-17 and neutrophil measurement, chemokine (C-X-C motif) ligand 1 immunohistochemistry, and confocal microscopy revealed increased numbers of IL-17-secreting cells in the nasal mucosa of the OVA/Poly(I:C) groups, which included natural killer cells, CD4 T cells, and neutrophils. In conclusion, we developed a mouse model of IL-17-dominant rhinitis using OVA together with Poly(I:C). This model will be useful in research on neutrophil- or IL-17-dominant rhinitis.

IL-17A Produced by Innate Lymphoid Cells Is Essential for Intestinal Ischemia-Reperfusion Injury

Ischemia-reperfusion (IR) injury to the small intestine following clamping of the superior mesenteric artery results in an intense local inflammatory response that is characterized by villous damage and neutrophil infiltration. IL-17A, a cytokine produced by a variety of cells in response to inflammatory cytokines released following tissue injury, has been implicated in IR injury. Using Il17a^-/- , Il23r^-/- , and Rorc^-/- mice and administration of anti-IL-17A and anti-IL-23 neutralizing Abs to wild-type mice, we demonstrate that intestinal IR injury depends on IL-17A and that IL-17A is downstream of the binding of autoantibody to ischemia-conditioned tissues and subsequent complement activation. Using bone marrow chimeras, we demonstrate that the IL-17A required for intestinal IR injury is derived from hematopoietic cells. Finally, by transferring autoantibody-rich sera into Rag2γc^-/- and Rag2^-/- mice, we demonstrate that innate lymphoid cells are the main producers of IL-17A in intestinal IR injury. We propose that local production of IL-17A by innate lymphoid cells is crucial for the development of intestinal IR injury and may provide a therapeutic target for clinical exploitation.

Cellular and molecular mechanisms of asthma and COPD

Asthma and chronic obstructive pulmonary disease (COPD) both cause airway obstruction and are associated with chronic inflammation of the airways. However, the nature and sites of the inflammation differ between these diseases, resulting in different pathology, clinical manifestations and response to therapy. In this review, the inflammatory and cellular mechanisms of asthma and COPD are compared and the differences in inflammatory cells and profile of inflammatory mediators are highlighted. These differences account for the differences in clinical manifestations of asthma and COPD and their response to therapy. Although asthma and COPD are usually distinct, there are some patients who show an overlap of features, which may be explained by the coincidence of two common diseases or distinct phenotypes of each disease. It is important to better understand the underlying cellular and molecular mechanisms of asthma and COPD in order to develop new treatments in areas of unmet need, such as severe asthma, curative therapy for asthma and effective anti-inflammatory treatments for COPD.

Sleep deprivation predisposes allergic mice to neutrophilic lung inflammation

BACKGROUND

Although different studies associated sleep deprivation (SD) with systemic inflammatory changes, the effect of sleep duration on the pathology of allergic chronic diseases is poorly understood.

OBJECTIVE

We sought to evaluate the influence of SD on allergen-induced pulmonary inflammation.

METHODS

Ovalbumin (OVA)-sensitized C57BL/6 mice were exposed to a first set of intranasal OVA challenge under SD or healthy sleep (HS) conditions, followed by a second OVA challenge, 1 week apart. Some groups were subjected to corticosteroid treatment with dexamethasone.

RESULTS

OVA-sensitized mice with SD had more severe airway inflammation than the allergic group with HS. Analysis of lung parenchyma revealed that the inflammation in allergic mice with SD was marked by an influx of neutrophils (mainly) and eosinophils and secretion of IL-6, TNF-α, and IL-17 in contrast to the eosinophilic inflammation and IL-4 production observed in allergic mice with HS. The same cytokine profile was observed in ex vivo culture of cervical lymph node cells and splenocytes, indicating that in allergic mice SD favors immune responses toward a proinflammatory T_H17 profile. This idea is supported by the fact that disruption of IL-17 signaling (IL-17 receptor A^-/-) prevented airway neutrophilia in allergic mice with SD. Furthermore, allergic mice with SD became refractory to corticosteroid treatment in contrast to the allergic group with HS.

CONCLUSION

Collectively, our data show that sleep quality participates in the progression of allergen-induced eosinophilic lung inflammation to corticosteroid-refractory neutrophilic manifestation.

Eotaxin and IL-4 levels are increased in induced sputum and correlate with sputum eosinophils in patients with nonasthmatic eosinophilic bronchitis

Nonasthmatic eosinophilic bronchitis (NAEB) is characterized by chronic cough and airway eosinophilic inflammation. Airway and systemic inflammation cytokine profile have not been comprehensively described in patients with NAEB.The aim of the study was to identify the cytokine profile in sputum and serum of NAEB patients. Furthermore, the relationship between cytokines and clinical features would be evaluated.Induced sputum and serum were collected from untreated NAEB patients and healthy subjects. The cytokine profile in sputum and serum was analyzed by a bead-based multiplex cytokine assay including 21 cytokines.The levels of EGF, eotaxin, GM-CSF, GRO, IFN-γ, IL-1β, IL-4, IL-6, IL-17A, IP-10, MIP-1α, and TNF-α in sputum were significantly higher in NAEB patients than that in healthy subjects (all P < 0.05). Values of area under the receiver operating characteristic curve (AUROC) of these cytokines were all above 0.750. The concentrations of eotaxin and IL-4 were positively correlated with sputum eosinophil percentage (r = 0.726, P = 0.002; r = 0.511, P = 0.043; respectively). No significant correlations between other cytokines (EGF, GM-CSF, GRO, IFN-γ, IL-1β, IL-6, IL-17A, IP-10, MIP-1α, and TNF-α) in sputum and sputum eosinophil percentage were found. The level of IL-4 in serum was slightly higher in NAEB patients than in healthy subjects. However, there was no correlation between serum IL-4 levels and sputum eosinophil percentage.We identified the cytokine profile in sputum and serum from NAEB patients. Sputum eotaxin and IL-4 could have the potential to become the biomarkers for NAEB and might be useful to assist in the diagnosis of NAEB.

Th17 regulating lower airway disease

PURPOSE OF REVIEW

Th17 lymphocytes are now widely believed to be critical for the regulation of various chronic immune diseases, including asthma and chronic obstructive pulmonary disease. In this review, we discuss the current understanding of the role of Th17 cells in the pathogenesis of different asthma phenotypes and chronic obstructive pulmonary disease.

RECENT FINDINGS

It has been recently reported that Th17 cells and also a new population of Th17/Th2 cells accumulate in bronchoalveolar lavage fluid of asthmatic patients, and positively correlated with airway obstruction and steroid resistance. These patients often have steroid resistant severe asthma and a predominant bronchial neutrophilic inflammation.

SUMMARY

Steroid resistant severe asthma with predominant bronchial neutrophilic inflammation could benefit from IL-17 targeted therapies. In this view, the definition of clinical phenotypes and inflammatory endotypes of asthma in each patient will be necessary for personalizing the therapeutic approach.

Chronic rhinosinusitis: the rationale for current treatments

INTRODUCTION

Chronic rhinosinusitis (CRS) is a broad clinical syndrome linked by mucosal inflammation. Primary treatment modalities are corticosteroids and antibiotics with surgery an option for failures, but the level of supporting evidence is generally low. The primary reason is that CRS is a symptom complex and not a specific disease. Areas covered: The primary treatment modalities for CRS are corticosteroids, antibiotics and surgery. Corticosteroids, which have very broad anti-inflammatory properties, also have the strongest evidence for efficacy. Antibiotics are likely effective in a subpopulation of patients but the various phenotypes and endotypes that make up CRS have thus far been poorly defined. Early surgery as well as biologics may also be more efficacious and cost effective in some phenotypes as well. Expert commentary: A better understanding of the inflammatory pathways that drive CRS will permit investigators to separate patient groups. This will allow for clinical trials that target specific subpopulations and more personalized therapy for CRS patients in the future.

TGF-β/BAMBI pathway dysfunction contributes to peripheral Th17/Treg imbalance in chronic obstructive pulmonary disease

BMP and activin membrane-bound inhibitor (BAMBI) is postulated to inhibit or modulate transforming growth factor β (TGF-β) signaling. Furthermore, strong upregulation of BAMBI expression following in vitro infection of chronic obstructive pulmonary disease (COPD) lung tissue has been demonstrated. In this study, we investigated whether TGF-β/BAMBI pathway is associated with COPD. Blood samples were obtained from 27 healthy controls (HC), 24 healthy smokers (HS) and 29 COPD patients. Elevated Th17/Treg ratios, and increased levels of BAMBI protein and mRNA (in plasma and CD4(+) T cells respectively), were observed in COPD compared with HC and HS. BAMBI expression was first observed on human CD4(+) T cells, with a typical membrane-bound pattern. The enhanced plasma BAMBI levels in COPD positively correlated with the increased plasma TGF-β1 levels and Th17/Treg ratio. Together, an impaired TGF-β/BAMBI pathway may promote the inflammation leading to Th17/Treg imbalance, which is a new mechanism in smokers who develop COPD.

COPD immunopathology

The immunopathology of chronic obstructive pulmonary disease (COPD) is based on the innate and adaptive inflammatory immune responses to the chronic inhalation of cigarette smoking. In the last quarter of the century, the analysis of specimens obtained from the lower airways of COPD patients compared with those from a control group of age-matched smokers with normal lung function has provided novel insights on the potential pathogenetic role of the different cells of the innate and acquired immune responses and their pro/anti-inflammatory mediators and intracellular signalling pathways, contributing to a better knowledge of the immunopathology of COPD both during its stable phase and during its exacerbations. This also has provided a scientific rationale for new drugs discovery and targeting to the lower airways. This review summarises and discusses the immunopathology of COPD patients, of different severity, compared with control smokers with normal lung function.

Human bronchial and parenchymal fibroblasts display differences in basal inflammatory phenotype and response to IL-17A

BACKGROUND

Chronic inflammation, typified by increased expression of IL-17A, together with airway and parenchymal remodelling are features of chronic lung diseases. Emerging evidence suggests that phenotypic heterogeneity of repair and inflammatory capacities of fibroblasts may contribute to the differential structural changes observed in different regions of the lung.

OBJECTIVE

To investigate phenotypic differences in parenchymal and bronchial fibroblasts, either in terms of inflammation and remodelling or the ability of these fibroblasts to respond to IL-17A.

METHODS

Four groups of primary fibroblasts were used: normal human bronchial fibroblast (NHBF), normal human parenchymal fibroblast (NHPF), COPD human bronchial fibroblast (CHBF) and COPD human parenchymal fibroblast (CHPF). Cytokine and extracellular matrix (ECM) expression were measured at baseline and after stimulation with IL-17A. Actinomycin D was used to measure cytokine mRNA stability.

RESULTS

At baseline, we observed higher protein production of IL-6 in NHPF than NHBF, but higher levels of IL-8 and GRO-α in NHBF. IL-17A induced a higher expression of GRO-α (CXCL1) and IL-6 in NHPF than in NHBF, and a higher level of IL-8 expression in NHBF. IL-17A treatment decreased the mRNA stability of IL-6 in NHBF when compared with NHPF. CHPF expressed higher protein levels of fibronectin, collagen-I and collagen-III than CHBF, NHBF and NHPF. IL-17A increased fibronectin and collagen-III protein only in NHPF and collagen-III protein production in CHBF and CHPF.

CONCLUSIONS AND CLINICAL RELEVANCE

These findings provide insight into the inflammatory and remodelling processes that may be related to the phenotypic heterogeneity of fibroblasts from airway and parenchymal regions and in their response to IL-17A.

Imbalance of Th17/Tregs in rats with smoke inhalation-induced acute lung injury

T helper (Th) 17 cells and CD4⁺ CD25⁺ regulatory T (Treg) cells are supposed to be critically involved in regulating autoimmune and inflammatory diseases. The aim of this study was to investigate the Th17/Treg pattern in rats with gunpowder smog-induced acute lung injury. Wistar rats were equally randomized to three groups: normal control group, ALI 6 h group (smoke inhalation for 6 h) and ALI 24 h group (smoke inhalation for 24 h). We observed changes in cell counting in bronchoalveolar lavage fluid (BALF), alveolar-capillary membrane permeability and lung tissue pathology. Moreover, rats in ALI 6 h and ALI 24 h group showed increased expression of Th17 cell and related cytokines (IL-17 A, IL-6, TGF-β and IL-23). Meanwhile, Treg prevalence and related cytokines (IL-10, IL-2 and IL-35) were decreased. Consequently, the ratio of Th17/Treg was higher after smoke inhalation. Additionally, Th1 cell decreased while Th2 cell increased at 6 h and 24 h after smoke inhalation. In conclusion, Th17/Treg imbalance exists in rats with smoke inhalation-induced acute lung injury, suggesting its potential role in the pathogenesis of this disease.

Asthma phenotyping: a necessity for improved therapeutic precision and new targeted therapies

Asthma is a common heterogeneous disease with a complex pathophysiology that carries a significant mortality rate and high morbidity. Current therapies based on inhaled corticosteroids and long-acting β-agonists remain effective in a large proportion of patients with asthma, but ~10% (considered to have 'severe asthma') do not respond to these treatments even at high doses or with the use of oral corticosteroids. Analytical clustering methods have revealed phenotypes that include dependence on high-dose corticosteroid treatment, severe airflow obstruction and recurrent exacerbations associated with an allergic background and late onset of disease. One severe phenotype is eosinophilic inflammation-predominant asthma, with late-onset disease, rhinosinusitis, aspirin sensitivity and exacerbations. Blood and sputum eosinophilia have been used to distinguish patients with high Th2 inflammation and to predict therapeutic response to treatments targeted towards Th2-associated cytokines. New therapies in the form of humanized antibodies against Th2 targets, such as anti-IgE, anti-IL4Rα, anti-IL-5 and anti-IL-13 antibodies, have shown encouraging results in terms of reduction in exacerbations and improvement in airflow in patients with a 'Th2-high' expression profile and blood eosinophilia. Research efforts are now focusing on elucidating the phenotypes underlying the non-Th2-high (or Th2-low) group, which constitutes ~50% of severe asthma cases. There is an increasing need to use biomarkers to indicate the group of patients who will respond to a specifically targeted treatment. The use of improved tools to measure activity of disease, a better definition of severe asthma and the delineation of inflammatory pathways with omics analyses using computational tools, will lead to better-defined phenotypes for specific therapies.

The footprint of TGF-β in airway remodeling of the mustard lung

Mustard lung is a major pulmonary complication in individuals exposed to sulfur mustard (SM) gas during the Iran-Iraq war. It shares common pathological and clinical features with some chronic inflammatory lung disorders, particularly chronic obstructive pulmonary disease (COPD). Airway remodeling, which is one of the main causes of lung dysfunction and the dominant phenomenon of chronic pulmonary diseases, is seen in the mustard lung. Among all mediators involved in the remodeling process, the transforming growth factor (TGF)-β plays a pivotal role in lung fibrosis and consequently in the airway remodeling. Regarding the high levels of this mediator detected in mustard lung patients, in the present study, we have discussed the possible roles of TGF-β in airway remodeling (including epithelial layer damage, subepithelial fibrosis and angiogenesis). Finally, based on TGF-β targeting, we have reviewed new airway remodeling therapeutic approaches.

Th17 response and its regulation in inflammatory upper airway diseases

Allergic rhinitis (AR) and chronic rhinosinusitis (CRS) are two widely prevalent inflammatory diseases in the upper airways. T cell immunity has been suggested to play an important pathogenic role in many chronic inflammatory diseases including inflammatory upper airway diseases. Inappropriate CD4(+) T cell responses, especially the dysregulation of the Th1/Th2 balance leading to excessive Th1 or Th2 cell activation, have been associated with allergic rhinitis and chronic rhinosinusitis. Nevertheless, recent studies suggest that IL-17A and IL-17A-producing Th17 cell subset, a distinct pro-inflammatory CD4(+) T cell lineage, may also play an important role in the pathophysiology of inflammatory upper airway diseases. Th17 cells may promote both eosinophilic and neutrophilic inflammation in AR and CRS. In addition, a few, but accumulating evidence shows that the Th17 responses can be tightly regulated by endogenous and exogenous substances in the context of AR and CRS. This review discusses recent advances in our understanding of the expression and function of the Th17 response and its regulation in inflammatory upper airway diseases, and the perspective for future investigation and clinical utility.

T-cell phenotypes in chronic rhinosinusitis with nasal polyps in Japanese patients

BACKGROUND

Chronic rhinosinusitis with nasal polyps is characterized by local inflammation and is categorized into two subtypes in Japan: eosinophilic chronic rhinosinusitis, and non-eosinophilic chronic rhinosinusitis. The objective of this study was to investigate the expression of key transcription factors for Treg and Th1/Th2/Th17 cells, in relation to the mRNA expression of representative cytokines in these two subtypes of chronic rhinosinusitis with nasal polyps.

METHODS

The expression of forkhead box P3 (FOXP3), T-box transcription factor (T-bet), GATA3, retinoid acid-related orphan receptor C (RORc), the suppressive cytokines TGF-β1 and IL-10, and Th1/Th2/Th17 cytokines (IFN-γ, IL-4, IL-5, IL-13, IL-17) were analyzed by means of RT-PCR in eosinophilic polyps. Eosinophilic polyps were defined as having an eosinophil count of more than 50 per microscopic field (×400 magnification) using five fields located in the subepithelial area of the polyps, while the non-eosinophilic polyps and controls did not fulfill this criteria. The numbers of T cells, CD4+ T cells, CD8+ T cells and Treg were histologically counted using sections that were immunostained for CD3, CD4, CD8, and FOXP3, respectively.

RESULTS

In eosinophilic polyps, we observed significantly fewer CD4+ T cells and CD8+ T cells, and lower GATA3, RORc and IL-10 mRNA expression, but a significantly higher IL-5, and IL-13 mRNA expression compared with controls, whereas FOXP3 and T-bet mRNA expression were not significantly different compared with controls. In non-eosinophilic polyps, FOXP3, IL-10, IL-17A, TGFβ1 and IFNγ mRNA expression was significantly higher compared with controls, whereas IL-4, 5 and 13 expression was not significantly different from controls.

CONCLUSION

We showed a reduction of GATA3 and RORc mRNA, low Treg-related cytokines and elevated Th2 cytokine levels in eosinophilic chronic rhinosinusitis, whereas we demonstrated the upregulation of Treg cells and increases of Th1 and Th17 cytokines in non-eosinophilic chronic rhinosinusitis in the Japanese population. The different mRNA expression profiles of Treg and Th1/Th2/Th17 signature transcription factors and cytokines between eosinophilic chronic rhinosinusitis and non-eosinophilic chronic rhinosinusitis suggests heterogeneity in the pathogenesis of chronic rhinosinusitis with nasal polyps.

Immunobiology of the critical asthma syndrome

It is now recognized that asthma incorporates a broad spectrum of syndromes with varying clinical manifestations. Future improvements in asthma treatment will require a clear characterization of these asthma phenotypes and the cellular mechanisms underlying these clinical manifestations. Herein, we will describe the current knowledge of asthma biology. This will include a review of the early pioneers in asthma and allergy, how this work led to our understanding of TH1 and TH2 cytokines, and the development of the "hygiene hypothesis." We will discuss the utility and limitations of the TH1-TH2 model of asthma in animal and human studies, and how this knowledge addresses controversies surrounding the hygiene hypothesis and other competing models. We will discuss novel therapies that have been developed based on mechanistic understanding of asthma pathobiology, including successes and shortcomings of these therapies. We will review the early work that led to the recognition of "asthma phenotypes." This will include the early discovery of various inflammatory subtypes in asthma and how these inflammatory subtypes correlate with response to therapy. Finally, we will describe recent discoveries in asthma biology that will include the role of the airway epithelium in asthma pathogenesis, novel cytokines important in asthma that may serve as novel therapeutic targets, and the identification of newly described innate immune cells and their role in asthma. Improved understanding of the complex biology underpinning the various asthma phenotypes is critical for our ability to optimize treatment for all patients that suffer from asthma and critical asthma syndromes.

Targeting the interleukin pathway in the treatment of asthma

Asthma is a common heterogeneous disease with a complex pathophysiology. Current therapies based on inhaled corticosteroids and longacting β2 agonists are effective in controlling asthma in most, but not all patients, with a few patients falling into the severe asthma category. Severe asthma is characterised by poor asthma control, recurrent exacerbations, and chronic airflow obstruction despite adequate and, in many cases, high-dose treatments. There is strong evidence supporting the role for interleukins derived from T-helper-2 (Th2) cells and innate lymphoid cells, such as interleukins 4, 5, and 13, as underlying the eosinophilic and allergic inflammatory processes in nearly half of these patients. An anti-IgE antibody, omalizumab, which binds to circulating IgE, a product of B cells from the actions of interleukin 4 and interleukin 13, is used as treatment for severe allergic asthma. Studies examining cytokine blockers such as anti-interleukin-5, anti-interleukin-4Rα, and anti-interleukin-13 monoclonal antibodies in patients with severe asthma with recurrent exacerbations and high blood eosinophil counts despite use of inhaled corticosteroids have reported improved outcomes in terms of exacerbations, asthma control, and forced expiratory volume in 1 s. The US Food and Drug Administration's recommendation to use an anti-interleukin-5 antibody for the treatment of severe eosinophilic asthma suggests that there will be a therapeutic place for these anti-Th2 agents. Biomarkers should be used to identify the right patients for such targeted approaches. More guidance will be needed as to which patients should receive each of these classes of selective antibody-based treatments. Currently, there is no treatment that targets the cytokines driving asthma associated with non-eosinophilic inflammation and low Th2 expression.

ILC2s and fungal allergy

Innate lymphoid cells (ILCs) have emerged recently as an important component of the immune system and the cell type that regulates mucosal immune responses and tissue homeostasis. Group 2 ILCs (ILC2s), a subset of ILCs, reside in various tissues and are characterized by their capacity to produce type 2 cytokines and tissue growth factors. These ILC2s play an important role in allergic immune responses by linking signals in the atmospheric environment to the immune system. Fungi are one of the major allergens associated with human asthma, and animal and in vitro models using the fungal allergens have provided significant information toward our understanding of the mechanisms of allergic disease. In mouse models of fungus-induced allergic airway inflammation, IL-33, IL-25, and TSLP are released by airway epithelial cells. Lung ILC2s that respond to these cytokines quickly produce a large quantity of type 2 cytokines, resulting in airway eosinophilia, mucus production, and airway hyperreactivity even in the absence of adaptive immune cells. Evidence also suggests that ILC2s interact with conventional immune cells, such as CD4⁺ T cells, and facilitate development of adaptive immune response and persistent airway inflammation. ILC2s are also present in respiratory mucosa in humans. Further investigations into the biology of ILC2s and their roles in the pathophysiology of allergic diseases will provide major conceptual advances in the field and may provide useful information toward development of new therapeutic strategies for patients.

Interleukin-17A promotes the formation of inflammation in the lung tissues of rats with pulmonary fibrosis

The aim of the present study was to investigate the effects of interleukin (IL)-17A in a rat model of pulmonary fibrosis. In total, 20 female Wistar rats were randomly divided into a normal saline (NS group) and a bleomycin group (BLM group). The BLM group rats were intratracheally instilled with BLM, while the NS group rats were intratracheally instilled with saline. In each group, half the rats were sacrificed at day 7 and day 28, respectively, following intratracheal instillation. Subsequently, hematoxylin and eosin and Masson's trichrome staining were performed to observe the pathological changes in the lung tissue, while the expression of IL-17A in the lung tissue was detected by immunohistochemistry. In addition, the bronchoalveolar lavage fluid (BALF) was collected and divided into two sections. One section was used for cell counting and classification, and an ELISA was performed to detect the concentration of IL-17A in the BALF. The additional section was used to separate, purify and cultivate alveolar macrophages (AMs). The concentration of IL-17A in the cultivating supernatant was detected by ELISA, and the mRNA expression levels of IL-17A in the AMs were detected using reverse transcription-polymerase chain reaction (RT-PCR). The results revealed that a considerable number of inflammatory cells had infiltrated into the alveolar cavity in the BLM group at day 7, and less alveolitis and more serious fibrosis were observed at day 28, as compared with the NS group. Furthermore, when compared with the NS group, the protein expression levels of IL-17A in the lung tissue were markedly higher in the BLM group at days 7 and 28 (higher at day 7; P<0.05). In addition, the total number of BALF cells in the BLM group was clearly higher at day 7 when compared with the NS group (P<0.05), although a normal level was re-established by day 28. The level of IL-17A in the BALF increased significantly at days 7 and 28 in the BLM group; however, when compared with the level at day 7, the concentration had decreased at day 28. When compared with the NS group, the protein expression levels of IL-17A in the BLM group were notably higher after 12, 24 and 48 h. In addition, the results of the RT-PCR assay revealed that the mRNA expression levels of IL-17A increased significantly at days 7 and 28 in the BLM group when compared with the NS group (P<0.05). Therefore, IL-17A was demonstrated to promote the development of pulmonary inflammation, which may be involved in the development of pulmonary fibrosis.

Group 2 innate lymphoid cells in the lung

As the first line of defense, innate immunity plays an important role in protecting the host against pathogens. Innate lymphoid cells (ILCs) are emerging as important effector cells in the innate immune system and the cell type that regulate immune and tissue homeostases. Group 2 ILCs (ILC2s) are a subset of ILCs and are characterized by their capacity to produce large quantities of type 2 cytokines and certain tissue growth factors. In animal models, lung ILC2s are involved in allergic airway inflammation induced by exposure to allergens even in the absence of CD4(+) T cells and are likely responsible for tissue repair and recovery after respiratory virus infection. ILC2s are also identified in various organs in humans, and the numbers are increased in mucosal tissues from patients with allergic disorders. Further investigations of this novel cell type will provide major conceptual advances in our understanding of the mechanisms of asthma and allergic diseases.

A 7-month cigarette smoke inhalation study in C57BL/6 mice demonstrates reduced lung inflammation and emphysema following smoking cessation or aerosol exposure from a prototypic modified risk tobacco product

Modified risk tobacco products (MRTP) are designed to reduce smoking-related health risks. A murine model of chronic obstructive pulmonary disease (COPD) was applied to investigate classical toxicology end points plus systems toxicology (transcriptomics and proteomics). C57BL/6 mice were exposed to conventional cigarette smoke (3R4F), fresh air (sham), or a prototypic MRTP (pMRTP) aerosol for up to 7 months, including a cessation group and a switching-to-pMRTP group (2 months of 3R4F exposure followed by fresh air or pMRTP for up to 5 months respectively). 3R4F smoke induced the typical adaptive changes in the airways, as well as inflammation in the lung, associated with emphysematous changes (impaired pulmonary function and alveolar damage). At nicotine-matched exposure concentrations of pMRTP aerosol, no signs of lung inflammation and emphysema were observed. Both the cessation and switching groups showed a similar reversal of inflammatory responses and no progression of initial emphysematous changes. A significant impact on biological processes, including COPD-related inflammation, apoptosis, and proliferation, was identified in 3R4F-exposed, but not in pMRTP-exposed lungs. Smoking cessation or switching reduced these perturbations to near sham-exposed levels. In conclusion, the mouse model indicated retarded disease progression upon cessation or switching to pMRTP which alone had no adverse effects.