Airway inflammation in asthma: key players beyond the Th2 pathway

Norisoboldine exerts antiallergic effects on IgE/ovalbumin-induced allergic asthma and attenuates FcεRI-mediated mast cell activation

Allergic asthma is an inflammatory lung disorder, and mast cells play crucial roles in the development of this allergic disease. Norisoboldine (NOR), the major isoquinoline alkaloid present in Radix Linderae, has received considerable attention because it has anti-inflammatory effects. Herein, the aim of this study was to explore the antiallergic effects of NOR on allergic asthma in mice and mast cell activation. In a murine model of ovalbumin (OVA)-induced allergic asthma, oral administration at 5 mg/kg body weight (BW) of NOR produced strong reductions in serum OVA-specific immunoglobulin E (IgE) levels, airway hyperresponsiveness, and bronchoalveolar lavage fluid (BALF) eosinophilia, while an increase in CD4+Foxp3+ T cells of the spleen was detected. Histological studies demonstrated that NOR treatment significantly ameliorated the progression of airway inflammation including the recruitment of inflammatory cells and mucus production by decreasing levels of histamine, prostaglandin D2 (PGD2), interleukin (IL)-4, IL-5, IL-6, and IL-13 in BALF. Furthermore, our results revealed that NOR (3 ∼ 30 μM) dose-dependently reduced expression of the high-affinity receptor for IgE (FcεRI) and the production of PGD2 and inflammatory cytokines (IL-4, IL-6, IL-13, and TNF-α), and also decreased degranulation of bone marrow-derived mast cells (BMMCs) activated by IgE/OVA. In addition, a similar suppressive effect on BMMC activation was observed by inhibition of the FcεRI-mediated c-Jun N-terminal kinase (JNK) signaling pathway using SP600125, a selective JNK inhibitor. Collectively, these results suggest that NOR may have therapeutic potential for allergic asthma at least in part through regulating the degranulation and the release of mediators by mast cells.

Economic impact of a more extensive use of FENO testing on the Italian population with asthma

BACKGROUND

Asthma is a common chronic inflammatory airway affecting over 260 million people worldwide, and characterized, in the large majority of cases, by the so-called "type 2 inflammation". Fractional exhaled nitric oxide (FE_NO) testing is noninvasive point-of-care tool to assess type 2 inflammation and therefore improve asthma management. It has been suggested to determine eligibility for a specific biologic therapy and predict likelihood to respond. The aim of this study was to estimate the overall economic impact of an extensive use of FE_NO testing on the Italian population with asthma, including extra costs of testing and savings generated by more appropriate prescriptions, increased adherence and lower frequency of exacerbations.

METHODS

A cost of illness analysis was firstly performed to estimate the yearly economic burden from the National Healthcare Service (NHS) perspective in Italy of the management of asthmatic patients with standard of care (SOC) according to the application of GINA (Global Initiative for Asthma) guidelines; then, we evaluated the changes in the economic burden in patient management by introducing FE_NO testing into clinical practice. The cost items considered were: visits/exams, exacerbations, drugs, management of adverse events caused by short-term oral corticosteroids use. Efficacy of FeNO test and SOC is based on literature evidence. Costs refer to published data or Diagnosis Related Group/outpatient tariffs.

RESULTS

Considering one asthma visit every 6 months, the total yearly cost for the management of patients with asthma in Italy is 1,599,217,876€ (409.07€ per patient), while for FE_NO testing strategy this figure is 1,395,029,747€ (356.84€ per patient). An increased utilization rate of FE_NO testing from 50 to 100% of patients may lead to savings for the NHS from about 102 to 204 million € compared to SOC.

CONCLUSIONS

Our study showed that FeNO testing strategy may improve the management of asthmatic patients leading to significant savings for the NHS.

Determination of the effects of advanced glycation end products receptor polymorphisms and its activation on structural cell responses and inflammation in asthma

BACKGROUND

Advanced glycation end products receptor (RAGE) is a pattern recognition receptor which attracted attention in chronic airway diseases recently. This study aimed to determine the association of RAGE with asthma and the cellular responses resulting from RAGE signaling pathway activation.

METHODS

Asthmatic (n = 362) and healthy (n = 134) children were genotyped by PCR-RFLP. Plasma sRAGE levels were determined by ELISA. Lung structural cells were stimulated with AGEs (advanced glycation end products) and control BSA. Expressions of cytokines and protein levels were determined by real-time PCR and ELISA.

RESULTS

: Gly82Ser and -374 T/A polymorphisms in RAGE gene were associated with lower plasma sRAGE levels (p < 0.001 and p < 0.025, respectively). AGE stimulation increased the expression of RAGE (p = 0.002), ICAM-1 (p = 0.010) and VCAM-1 (p = 0.002) in endothelial cells; TIMP-1 (p = 0.003) and MCP-1 (p = 0.005) in fibroblasts. AGE stimulation increased protein levels of IL-6 (p < 0.001) in endothelial cells; VEGF (p = 0.025) and IL-8 (p < 0.001) in fibroblasts; IL-1b (p < 0.001) and VEGF (p = 0.007) in epithelial cells.

DISCUSSION

Activation of RAGE pathway may contribute to asthma pathogenesis by increasing the expression of several asthmarelated genes. These findings suggest that suppression of RAGE signaling may be an alternative candidate for treating asthma.

Airway smooth muscle in contractility and remodeling of asthma: potential drug target mechanisms

INTRODUCTION

Asthma is characterized by enhanced airway contractility and remodeling where airway smooth muscle (ASM) plays a key role, modulated by inflammation. Understanding the mechanisms by which ASM contributes to these features of asthma is essential for the development of novel asthma therapies.

AREAS COVERED

Inflammation in asthma contributes to a multitude of changes within ASM including enhanced airway contractility, proliferation, and fibrosis. Altered intracellular calcium ([Ca²⁺]_i) regulation or Ca²⁺ sensitization contributes to airway hyperreactivity. Increased airway wall thickness from ASM proliferation and fibrosis contributes to structural changes seen with asthma.

EXPERT OPINION

ASM plays a significant role in multiple features of asthma. Increased ASM contractility contributes to hyperresponsiveness, while altered ASM proliferation and extracellular matrix production promote airway remodeling both influenced by inflammation of asthma and conversely even influencing the local inflammatory milieu. While standard therapies such as corticosteroids or biologics target inflammation, cytokines, or their receptors to alleviate asthma symptoms, these approaches do not address the underlying contribution of ASM to hyperresponsiveness and particularly remodeling. Therefore, novel therapies for asthma need to target abnormal contractility mechanisms in ASM and/or the contribution of ASM to remodeling, particularly in asthmatics resistant to current therapies.

IL-5 and GM-CSF, but Not IL-3, Promote the Proliferative Properties of Inflammatory-like and Lung Resident-like Eosinophils in the Blood of Asthma Patients

Blood eosinophils can be described as inflammatory-like (iEOS-like) and lung-resident-like (rEOS-like) eosinophils. This study is based on the hypothesis that eosinophilopoetins such as interleukin (IL)-3 and IL-5 and granulocyte-macrophage colony-stimulating factor (GM-CSF) alter the proliferative properties of eosinophil subtypes and may be associated with the expression of their receptors on eosinophils. We investigated 8 individuals with severe nonallergic eosinophilic asthma (SNEA), 17 nonsevere allergic asthma (AA), and 11 healthy subjects (HS). For AA patients, a bronchial allergen challenge with Dermatophagoides pteronyssinus was performed. Eosinophils were isolated from peripheral blood using high-density centrifugation and magnetic separation methods. The subtyping of eosinophils was based on magnetic bead-conjugated antibodies against L-selectin. Preactivation by eosinophilopoetins was performed by incubating eosinophil subtypes with IL-3, IL-5, and GM-CSF, and individual combined cell cultures were prepared with airway smooth muscle (ASM) cells. ASM cell proliferation was assessed using an Alamar blue assay. The gene expression of eosinophilopoetin receptors was analyzed with a qPCR. IL-5 and GM-CSF significantly enhanced the proliferative properties of iEOS-like and rEOS-like cells on ASM cells in both SNEA and AA groups compared with eosinophils not activated by cytokines (p < 0.05). Moreover, rEOS-like cells demonstrated a higher gene expression of the IL-3 and IL-5 receptors compared with iEOS-like cells in the SNEA and AA groups (p < 0.05). In conclusion: IL-5 and GM-CSF promote the proliferative properties of iEOS-like and rEOS-like eosinophils; however, the effect of only IL-5 may be related to the expression of its receptors in asthma patients.

The potential roles of interleukin-25 in infectious diseases

Interleukin-25 (IL-25), also known as IL-17E, is a recently identified cytokine of the IL-17 family. Numerous studies illustrated that the expression of IL-25 is regulated by multiple pathogens, including parasitic, viral, and bacterial infections. IL-25 has a dual function in infectious diseases. On the one hand, IL-25 activates type 2 immunity via the relevant cytokines, including IL-4, IL-5, and IL-13, which are associated with the development of pathogenic infection-related allergic diseases. On the other hand, IL-25 involves in the recruitment of group 2 innate lymphoid cells (ILC2) to enhanced T helper 2 (Th2) cell differentiation, which are important to the clearance of pathogens. However, the precise roles of IL-25 in infectious diseases remain largely unknown. Thus, the current review will shed light on the pivotal roles of IL-25 in infectious diseases.

Astragaloside IV suppresses inflammatory response via suppression of NF-κB, and MAPK signalling in human bronchial epithelial cells

CONTEXT

Astragaloside IV isolated from Astragalus membranaceus (Fisch.), which was reported to have anti-tumor, anti-asthma, and suppressed cigarette smoke-induced lung inflammation in mice.

OBJECTIVES

This study investigated whether astragaloside IV reduced the expression of inflammatory mediators and oxidative stress in BEAS-2B cells.

METHODS

BEAS-2B cells treated with astragaloside IV, and then stimulated with TNF-α or TNF-α/IL-4. The levels of cytokine and chemokine were analysed with ELISA and real-time PCR.

RESULTS

Astragaloside IV significantly inhibited the levels of CCL5, MCP-1, IL-6 and IL-8. Astragaloside IV also reduced ICAM-1 expression for blocked THP-1 monocyte adhesion to BEAS-2B cells. Furthermore, astragaloside IV attenuated the phosphorylation of MAPK, and reduced the translocation of p65 into the nucleus. Astragaloside IV could increase the expression of HO-1 and Nrf2 for promoting the oxidant protective effect.

CONCLUSION

Aastragaloside IV has an anti-inflammatory and oxidative effect via regulated NF-κB, MAPK and HO-1/Nrf2 signalling pathways in human bronchial epithelial cells.

CTNNAL1 participates in the regulation of mucus overproduction in HDM‐induced asthma mouse model through the YAP‐ROCK2 pathway

Our previous study indicated that adhesion molecule catenin alpha‐like 1(CTNNAL1) is downregulated in airway epithelial cells of asthma patients and asthma animal model but little is known about how the CTNNAL1 affects asthma pathogenesis. To reveal the direct relationship between asthma and CTNNAL1, CTNNAL1‐deficient mouse model in bronchopulmonary tissue was constructed by introducing CTNNAL1‐siRNA sequence using adeno‐associated virus (AAV) as vector. The mouse model of asthma was established by stimulation of house dust mite (HDM). After HDM‐challenged, there was marked airway inflammation, especially mucus hypersecretion in the CTNNAL1‐deficient mice. In addition, the CTNNAL1‐deficient mice exhibited an increase of lung IL‐4 and IL‐13 levels, as well as a significant increase of goblet cell hyperplasia and MUC5AC after HDM exposure. The expression of Yes‐associated protein (YAP), protein that interacted with α‐catenin, was downregulated after CTNNAL1 silencing and was upregulated due to its overexpression. In addition, the interaction between CTNNAL1 and YAP was confirmed by CO‐IP. Besides, inhibition of YAP could decrease the secretion of MUC5AC, IL‐4 and IL‐13 in CTNNAL1‐deficient 16HBE14o‐cells. Above results indicated us that CTNNAL1 regulated mucus hypersecretion through YAP pathway. In addition, the expression of ROCK2 increased when CTNNAL1 was silenced and decreased after YAP silencing, and inhibition of YAP decreased the expression of ROCK2 in CTNNAL1‐deficient HBE cells. Inhibition of ROCK2 decreased MUC5AC expression and IL‐13 secretion. In all, our study demonstrates that CTNNAL1 plays an important role in HDM‐induced asthma, mediating mucus secretion through the YAP‐ROCK2 pathway.

Dysregulated Notch Signaling in the Airway Epithelium of Children with Wheeze

The airway epithelium of children with wheeze is characterized by defective repair that contributes to disease pathobiology. Dysregulation of developmental processes controlled by Notch has been identified in chronic asthma. However, its role in airway epithelial cells of young children with wheeze, particularly during repair, is yet to be determined. We hypothesized that Notch is dysregulated in primary airway epithelial cells (pAEC) of children with wheeze contributing to defective repair. This study investigated transcriptional and protein expression and function of Notch in pAEC isolated from children with and without wheeze. Primary AEC of children with and without wheeze were found to express all known Notch receptors and ligands, although pAEC from children with wheeze expressed significantly lower NOTCH2 (10-fold, p = 0.004) and higher JAG1 (3.5-fold, p = 0.002) mRNA levels. These dysregulations were maintained in vitro and cultures from children with wheeze displayed altered kinetics of both NOTCH2 and JAG1 expression during repair. Following Notch signaling inhibition, pAEC from children without wheeze failed to repair (wound closure rate of 76.9 ± 3.2%). Overexpression of NOTCH2 in pAEC from children with wheeze failed to rescue epithelial repair following wounding. This study illustrates the involvement of the Notch pathway in airway epithelial wound repair in health and disease, where its dysregulation may contribute to asthma development.

Autophagy Modulators From Chinese Herbal Medicines: Mechanisms and Therapeutic Potentials for Asthma

Asthma has become a global health issue, suffering more than 300 million people in the world, which is a heterogeneous disease, usually characterized by chronic airway inflammation and airway hyperreactivity. Combination of inhaled corticosteroids (ICS) and long acting β-agonists (LABA) can relieve asthma symptoms and reduce the frequency of exacerbations, especially for patients with refractory asthma, but there are limited treatment options for people who do not gain control on combination ICS/LABA. The increase in ICS dose generally provides little additional benefit, and there is an increased risk of side effects. Therefore, therapeutic interventions integrating the use of different agents that focus on different targets are needed to overcome this set of diseases. Some findings suggest autophagy is closely correlated with the severity of asthma through eosinophilic inflammation, and its modulation may provide novel therapeutic approaches for severe allergic asthma. The chinese herbal medicine (CHM) have been demonstrated clinically as potent therapeutic interventions for asthma. Moreover some reports have found that the bioactive components isolated from CHM could modulate autophagy, and exhibit potent Anti-inflammatory activity. These findings have implied the potential for CHMs in asthma or allergic inflammation therapy via the modulation of autophagy. In this review, we discuss the basic pathomechanisms underpinning asthma, and the potential role of CHMs in treating asthma with modulating autophagy.

ILC2 Cells Promote Th2 Cell Differentiation in AECOPD Through Activated Notch-GATA3 Signaling Pathway

This study is to investigate the capacity of type 2 innate lymphoid cells (ILC2s) in regulating the Th2 type adaptive immune response of acute exacerbation of chronic obstructive pulmonary disease (AECOPD). The study enrolled healthy people, stable chronic obstructive pulmonary disease (COPD) patients, and AECOPD patients. Flow cytometry was used to detect Th2 and ILC2 cells in the peripheral blood. In addition, ILC2s from the peripheral blood of AECOPD patients were stimulated with PBS, IL-33, Jagged1, DAPT, IL-33+Jagged1, IL-33+DAPT, and IL-33+Jagged-1+DAP in vitro. The levels of cytokines in the culture supernatant were detected by ELISA and the culture supernatant was used to culture CD4 ⁺ T cells. The mRNA and protein levels of Notch1, hes1, GATA3, RORα, and NF-κB of ILC2s were detected by real-time PCR and Western blot. The proportion of Th2 and ILC2s was significantly increased in the peripheral blood of AECOPD patients, alone with the increased Notch1, hes1, and GATA3 mRNA levels. In vitro results showed that the mRNA and protein levels of Notch1, hes1, GATA3 and NF-κB were significantly increased after stimulation with Notch agonist, meanwhile, the level of type 2 cytokines were increased in the supernatant of cells stimulated with Notch agonist, and significantly promoted differentiation of Th2 cells in vitro. Disruption of Notch pathway weakened GATA3 expression and cytokine production, and ultimately affected the differentiation of Th2 cells. In conclusion, our results suggest that ILC2s can promote Th2 cell differentiation in AECOPD via activated Notch-GATA3 signal pathway.

Review - Nutraceuticals Can Target Asthmatic Bronchoconstriction: NADPH Oxidase-Dependent Oxidative Stress, RhoA and Calcium Dynamics

Activation of various isoforms of NADPH oxidase contributes to the pathogenesis of asthma at multiple levels: promoting hypercontractility, hypertrophy, and proliferation of airway smooth muscle; enabling lung influx of eosinophils via VCAM-1; and mediating allergen-induced mast cell activation. Free bilirubin, which functions physiologically within cells as a feedback inhibitor of NADPH oxidase complexes, has been shown to have a favorable impact on each of these phases of asthma pathogenesis. The spirulina chromophore phycocyanobilin (PhyCB), a homolog of bilirubin’s precursor biliverdin, can mimic the inhibitory impact of biliverdin/bilirubin on NADPH oxidase activity, and spirulina’s versatile and profound anti-inflammatory activity in rodent studies suggests that PhyCB may have potential as a clinical inhibitor of NADPH oxidase. Hence, spirulina or PhyCB-enriched spirulina extracts merit clinical evaluation in asthma. Promoting biosynthesis of glutathione and increasing the expression and activity of various antioxidant enzymes – as by supplementing with N-acetylcysteine, Phase 2 inducers (eg, lipoic acid), selenium, and zinc – may also blunt the contribution of oxidative stress to asthma pathogenesis. Nitric oxide (NO) and hydrogen sulfide (H₂S) work in various ways to oppose pathogenic mechanisms in asthma; supplemental citrulline and high-dose folate may aid NO synthesis, high-dose biotin may mimic and possibly potentiate NO’s activating impact on soluble guanylate cyclase, and NAC and taurine may boost H₂S synthesis. The amino acid glycine has a hyperpolarizing effect on airway smooth muscle that is bronchodilatory. Insuring optimal intracellular levels of magnesium may modestly blunt the stimulatory impact of intracellular free calcium on bronchoconstriction. Nutraceutical regimens or functional foods incorporating at least several of these agents may have utility as nutraceutical adjuvants to standard clinical management of asthma.

[The basophil: From control of immunity to control of leukemias]

The basophils, first described by Paul Ehlrich in 1879, are rare circulating cells, representing approximately 0.01 to 0.3% of the blood leukocytes. Until recently, these cells have been neglected because of their minority status among immune cells and because they show some similarities to mast cells residing in tissues. However, basophils and mast cells are now recognized as distinct cell lines and it appears that basophils have important and non-redundant functions, distinct from those of mast cells. On the one hand, basophils have beneficial contribution to protective immunity, in particular against parasitic infections. On the other hand, basophils are involved in the development of various benign and malignant pathologies, ranging from allergy to certain leukemias. Basophils interact with other immune cells or neoplastic cells through direct contacts or soluble mediators, such as cytokines and proteases, thus contributing to the regulation of the immune system but also to allergic responses, and probably to the process of neoplastic transformation. In this review, we will develop recent knowledge on the involvement of basophils in the modulation of innate and adaptive immunity. We will then describe the benign or malignant circumstances in which an elevation of circulating basophils can be observed. Finally, we will discuss the role played by these cells in the pathophysiology of certain leukemias, particularly during chronic myeloid leukemia.

New Avenues for Phosphodiesterase Inhibitors in Asthma

Introduction

Phosphodiesterases (PDEs) are isoenzymes ubiquitously expressed in the lungs where they catalyse cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (GMP), which are fundamental second messengers in asthma, thereby regulating the intracellular concentrations of these cyclic nucleotides, their signaling pathways and, consequently, myriad biological responses. The superfamily of PDEs is composed of 11 families with a distinct substrate specificity, molecular structure and subcellular localization. Experimental studies indicate a possible role in asthma mainly for PDE3, PDE4, PDE5 and PDE7. Consequently, drugs that inhibit PDEs may offer novel therapeutic options for the treatment of this disease.

Areas Covered

In this article, we describe the progress made in recent years regarding the possibility of using PDE inhibitors in the treatment of asthma.

Expert Opinion

Many data indicate the potential benefits of PDE inhibitors as an add-on treatment especially in severe asthma due to their bronchodilator and/or anti-inflammatory activity, but no compound has yet reached the market as asthma treatment mainly because of their limited tolerability. Therefore, there is a growing interest in developing new PDE inhibitors with an improved safety profile. In particular, the research is focused on the development of drugs capable of interacting simultaneously with different PDEs, or to be administered by inhalation. CHF 6001 and RPL554 are the only molecules that currently are under clinical development but there are several new agents with interesting pharmacological profiles. It will be stimulating to assess the impact of such agents on individual treatable traits in specially designed studies.

Emerging role of mitochondria in airborne particulate matter-induced immunotoxicity

The immune system is one of the primary targets of airborne particulate matter. Recent evidence suggests that mitochondria lie at the center of particulate matter-induced immunotoxicity. Particulate matter can directly interact with mitochondrial components (proteins, lipids, and nucleic acids) and impairs the vital mitochondrial processes including redox mechanisms, fusion-fission, autophagy, and metabolic pathways. These disturbances impede different mitochondrial functions including ATP production, which acts as an important platform to regulate immunity and inflammatory responses. Moreover, the mitochondrial DNA released into the cytosol or in the extracellular milieu acts as a danger-associated molecular pattern and triggers the signaling pathways, involving cGAS-STING, TLR9, and NLRP3. In the present review, we discuss the emerging role of mitochondria in airborne particulate matter-induced immunotoxicity and its myriad biological consequences in health and disease.

Airway epithelial integrin β4 suppresses allergic inflammation by decreasing CCL17 production

Airway epithelial cells (AECs) play a key role in asthma susceptibility and severity. Integrin β4 (ITGB4) is a structural adhesion molecule that is down-regulated in the airway epithelium of asthma patients. Although a few studies hint toward the role of ITGB4 in asthmatic inflammation pathogenesis, their specific resultant effects remain unexplored. In the present study, we determined the role of ITGB4 of AECs in the regulation of Th2 response and identified the underpinning molecular mechanisms. We found that ITGB4 deficiency led to exaggerated lung inflammation and AHR with higher production of CCL17 in house dust mite (HDM)-treated mice. ITGB4 regulated CCL17 production in AECs through EGFR, ERK and NF-κB pathways. EFGR-antagonist treatment or the neutralization of CCL17 both inhibited exaggerated pathological marks in HDM-challenged ITGB4-deficient mice. Together, these results demonstrated the involvement of ITGB4 deficiency in the development of Th2 responses of allergic asthma by down-regulation of EGFR and CCL17 pathway in AECs.

Helminthostachys zeylanica Water Extract Ameliorates Airway Hyperresponsiveness and Eosinophil Infiltration by Reducing Oxidative Stress and Th2 Cytokine Production in a Mouse Asthma Model

Helminthostachys zeylanica is a traditional folk herb used to improve inflammation and fever in Taiwan. Previous studies showed that H. zeylanica extract could ameliorate lipopolysaccharide-induced acute lung injury in mice. The aim of this study was to investigate whether H. zeylanica water (HZW) and ethyl acetate (HZE) extracts suppressed eosinophil infiltration and airway hyperresponsiveness (AHR) in asthmatic mice, and decreased the inflammatory response and oxidative stress in tracheal epithelial cells. Human tracheal epithelial cells (BEAS-2B cells) were pretreated with various doses of HZW or HZE (1 μg/ml-10 μg/ml), and cell inflammatory responses were induced with IL-4/TNF-α. In addition, female BALB/c mice sensitized with ovalbumin (OVA), to induce asthma, were orally administered with HZW or HZE. The result demonstrated that HZW significantly inhibited the levels of proinflammatory cytokines, chemokines, and reactive oxygen species in activated BEAS-2B cells. HZW also decreased ICAM-1 expression and blocked monocytic cells from adhering to inflammatory BEAS-2B cells in vitro. Surprisingly, HZW was more effective than HZE in suppressing the inflammatory response in BEAS-2B cells. Our results demonstrated that HZW significantly decreased AHR and eosinophil infiltration, and reduced goblet cell hyperplasia in the lungs of asthmatic mice. HZW also inhibited oxidative stress and reduced the levels of Th2 cytokines in bronchoalveolar lavage fluid. Our findings suggest that HZW attenuated the pathological changes and inflammatory response of asthma by suppressing Th2 cytokine production in OVA-sensitized asthmatic mice.

Exacerbation of Allergic Airway Inflammation in Mice Lacking ECTO-5'-Nucleotidase (CD73)

The airways are a target tissue of type I allergies and atopy is the main etiological factor of bronchial asthma. A predisposition to allergy and individual response to allergens are dependent upon environmental and host factors. Early studies performed to clarify the role of extracellular adenosine in the airways highlighted the importance of adenosine-generating enzymes CD73, together with CD39, as an innate protection system against lung injury. In experimental animals, deletion of CD73 has been associated with immune and autoimmune diseases. Our experiments have been performed to investigate the role of CD73 in the assessment of allergic airway inflammation following sensitization. We found that in CD73^−/− mice sensitization, induced by subcutaneous ovalbumin (OVA) administration, increased signs of airway inflammation and atopy developed, characterized by high IgE plasma levels and increased pulmonary cytokines, reduced frequency of lung CD4⁺CD25+Foxp3+ T cells, but without bronchial hyperreactivity, compared to sensitized wild type mice. Our results provide evidence that the lack of CD73 causes an uncontrolled allergic sensitization, suggesting that CD73 is a key molecule at the interface between innate and adaptive immune response. The knowledge of host immune factors controlling allergic sensitization is of crucial importance and might help to find preventive interventions that could act before an allergy develops.

Role of Farnesoid X Receptor in the Pathogenesis of Respiratory Diseases

Farnesoid X receptor (FXR) is a bile acid receptor encoded by the Nr1h4 gene. FXR plays an important role in maintaining the stability of the internal environment and the integrity of many organs, including the liver and intestines. The expression of FXR in nondigestible tissues other than in the liver and small intestine is known as the expression of “nonclassical” bile acid target organs, such as blood vessels and lungs. In recent years, several studies have shown that FXR is widely involved in the pathogenesis of various respiratory diseases, such as chronic obstructive pulmonary disease, bronchial asthma, and idiopathic pulmonary fibrosis. Moreover, a number of works have confirmed that FXR can regulate the bile acid metabolism in the body and exert its anti-inflammatory and antifibrotic effects in the airways and lungs. In addition, FXR may be used as a potential therapeutic target for some respiratory diseases. For example, FXR can regulate the tumor microenvironment by regulating the balance of inflammatory and immune responses in the body to promote the occurrence and development of non-small-cell lung cancer (NSCLC), thereby being considered a potential target for immunotherapy of NSCLC. In this article, we provide an overview of the internal relationship between FXR and respiratory diseases to track the progress that has been achieved thus far in this direction and suggest potential therapeutic prospects of FXR in respiratory diseases.

Monocyte chemotactic protein-inducing protein 1 negatively regulating asthmatic airway inflammation and mucus hypersecretion involving γ-aminobutyric acid type A receptor signaling pathway in vivo and in vitro

BACKGROUND

Mounting evidence, consistent with our previous study, showed that γ-aminobutyric acid type A receptor (GABAAR) played an indispensable role in airway inflammation and mucus hypersecretion in asthma. Monocyte chemotactic protein-inducing protein 1 (MCPIP1) was a key negative regulator of inflammation. Recent studies showed that inflammation was largely suppressed by enhanced MCPIP1 expression in many inflammatory diseases. However, the role and potential mechanism of MCPIP1 in airway inflammation and mucus hypersecretion in asthma were still not well studied. This study was to explore the role of MCPIP1 in asthmatic airway inflammation and mucus hypersecretion in both mice and BEAS-2B cells, and its potential mechanism.

METHODS

In vivo, mice were sensitized and challenged by ovalbumin (OVA) to induce asthma. Airway inflammation and mucus secretion were analyzed. In vitro, BEAS-2B cells were chosen. Interleukin (IL)-13 was used to stimulate inflammation and mucus hypersecretion in cells. MCPIP1 Lentiviral vector (LA-MCPIP1) and plasmid-MCPIP1 were used to up-regulate MCPIP1 in lung and cells, respectively. MCP-1, thymic stromal lymphopoietin (TSLP), mucin 5AC (MUC5AC), MCPIP1, and GABAARβ2 expressions were measured in both lung and BEAS-2B cells. Immunofluorescence staining was performed to observe the expression of GABAARβ2 in cells.

RESULTS

MCPIP1 was up-regulated by LA-MCPIP1 (P < 0.001) and plasmid-MCPIP1 (P < 0.001) in lung and cells, respectively. OVA-induced airway inflammation and mucus hypersecretion, OVA-enhanced MCP-1, TSLP, MUC5AC, and GABAARβ2 expressions, and OVA-reduced MCPIP1 were significantly blunted by LA-MCPIP1 in mice (all P < 0.001). IL-13-enhanced MCP-1, TSLP, MUC5AC, and GABAARβ2 expressions, and IL-13-reduced MCPIP1 were markedly abrogated by plasmid-MCPIP1 in BEAS-2B cells (all P < 0.001).

CONCLUSION

The results of this study suggested that OVA and IL-13-induced airway inflammation and mucus hypersecretion were negatively regulated by MCPIP1 in both lung and BEAS-2B cells, involving GABAAR signaling pathway.

Anti-Inflammatory Activity and ROS Regulation Effect of Sinapaldehyde in LPS-Stimulated RAW 264.7 Macrophages

We evaluated the anti-inflammatory effects of SNAH in lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophages by performing nitric oxide (NO) assays, cytokine enzyme-linked immunosorbent assays, Western blotting, and real-time reverse transcription-polymerase chain reaction analysis. SNAH inhibited the production of NO (nitric oxide), reactive oxygen species (ROS), tumor necrosis factor (TNF)-α, and interleukin (IL)-6. Additionally, 100 μM SNAH significantly inhibited total NO and ROS inhibitory activity by 93% (p < 0.001) and 34% (p < 0.05), respectively. Protein expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) stimulated by LPS were also decreased by SNAH. Moreover, SNAH significantly (p < 0.001) downregulated the TNF-α, IL-6, and iNOS mRNA expression upon LPS stimulation. In addition, 3–100 µM SNAH was not cytotoxic. Docking simulations and enzyme inhibitory assays with COX-2 revealed binding scores of −6.4 kcal/mol (IC₅₀ = 47.8 μM) with SNAH compared to −11.1 kcal/mol (IC₅₀ = 0.45 μM) with celecoxib, a known selective COX-2 inhibitor. Our results demonstrate that SNAH exerts anti-inflammatory effects via suppression of ROS and NO by COX-2 inhibition. Thus, SNAH may be useful as a pharmacological agent for treating inflammation-related diseases.

P53 in the impaired lungs

Our laboratory is focused on investigating the supportive role of P53 towards the maintenance of lung homeostasis. Acute lung injury, acute respiratory distress syndrome, chronic obstructive pulmonary disease, pulmonary fibrosis, bronchial asthma, pulmonary arterial hypertension, pneumonia and tuberculosis are respiratory pathologies, associated with dysfunctions of this endothelium defender (P53). Herein we review the evolving role of P53 towards the aforementioned inflammatory disorders, to potentially reveal new therapeutic possibilities in pulmonary disease.

Mechanopharmacology of Rho-kinase antagonism in airway smooth muscle and potential new therapy for asthma

The principle of mechanopharmacology of airway smooth muscle (ASM) is based on the premise that physical agitation, such as pressure oscillation applied to an airway, is able to induce bronchodilation by reducing contractility and softening the cytoskeleton of ASM. Although the underlying mechanism is not entirely clear, there is evidence to suggest that large-amplitude stretches are able to disrupt the actomyosin interaction in the crossbridge cycle and weaken the cytoskeleton in ASM cells. Rho-kinase is known to enhance force generation and strengthen structural integrity of the cytoskeleton during smooth muscle activation and plays a key role in the maintenance of force during prolonged muscle contractions. Synergy in relaxation has been observed when the muscle is subject to oscillatory length change while Rho-kinase is pharmacologically inhibited. In this review, inhibition of Rho-kinase coupled to therapeutic pressure oscillation applied to the airways is explored as a combination treatment for asthma.

Mast Cell Biology at Molecular Level: a Comprehensive Review

Mast cells (MCs) are portions of the innate and adaptive immune system derived from bone marrow (BM) progenitors that are rich in cytoplasmic granules. MC maturation, phenotype, and function are determined by their microenvironment. MCs accumulate at inflammatory sites associated with atopy, wound healing, and malignancies. They interact with the external environment and are predominantly located in close proximity of blood vessels and sensory nerves. MCs are key initiators and modulators of allergic, anaphylactic, and other inflammatory reactions, by induction of vasodilation, promoting of vascular permeability, recruitment of inflammatory cells, facilitation of adaptive immune responses, and modulation of angiogenesis, and fibrosis. They express a wide range of receptors, e.g., for IgE (FcεRI), IgG (FcγR), stem cell factor (SCF) (KIT receptor or CD117), complement (including C5aR), and cytokines, that upon activation trigger various signaling pathways. The final consequence of such ligand receptor-based activation of MCs is the release of a broad array of mediators which are classified in three categories. While some mediators are preformed and remain stored in granules such as heparin, histamine, and enzymes mainly chymase and tryptase, others are de novo synthesized only after activation including LTB4, LTD4, PDG2, and PAF, and the cytokines IL-10, IL-8, IL-5, IL-3, IL-1, GM-CSF, TGF-β, VEGF, and TNF-α. Depending on the stimulus, MCs calibrate their pattern of mediator release, modulate the amplification of allergic inflammation, and are involved in the resolution of the immune responses. Here, we review recent findings and reports that help to understand the MC biology, pathology, and physiology of diseases with MC involvement.

Targeted biologic therapy for asthma

BACKGROUND

Asthma is a common and potentially serious condition affecting 300 million people worldwide. For many years, we have relied on a one-size-fits-all approach to its management, using corticosteroids and bronchodilators for all symptomatic patients. However, with more recent advances, it has become clear that asthma is a heterogeneous condition with multiple different underlying pathways. Understanding the different subtypes will be a key to giving us the ability to intervene in a targeted way to personalize care for patients with asthma.

SOURCES OF DATA

Key published literature, guidelines and trials from clinicaltrials.gov.

AREAS OF AGREEMENT

The most widely studied of these subtypes is T2 high eosinophilic asthma, for which there are an increasing number of biologic therapies available. T2 high asthma is associated with the cytokines interleukin (IL)-4, IL-5 and IL-13, for each of which biologics have been developed.

AREAS OF CONTROVERSY

It is currently unclear which of the available biologics provides superior efficacy. It is also unclear how to select which biologic for which patient.

GROWING POINTS

Head-to-head trials of the available T2 biologics will be important to determine superiority, and a suggested order for trialling biologics. Going further than this, we would like to see further analyses of available biologics to allow us to predict responders from non-responders in advance of administering therapy.

AREAS TIMELY FOR DEVELOPING RESEARCH

Non-eosinophilic T2 low asthma is an area that is under-researched and for which there are few treatments available. It is likely that there are different subtypes in this category of asthma and unravelling what these are will be crucial to developing effective treatments.

PDE3 Inhibition Reduces Epithelial Mast Cell Numbers in Allergic Airway Inflammation and Attenuates Degranulation of Basophils and Mast Cells

Epithelial mast cells are generally present in the airways of patients with allergic asthma that are inadequately controlled. Airway mast cells (MCs) are critically involved in allergic airway inflammation and contribute directly to the main symptoms of allergic patients. Phosphodiesterase 3 (PDE3) tailors signaling of cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP), which are critical intracellular second messenger molecules in various signaling pathways. This paper investigates the pathophysiological role and disease-modifying effects of PDE3 in mouse bone marrow-derived MCs (bmMCs), human LAD2- and HMC1 mast cell lines, human blood basophils, and peripheral blood-derived primary human MCs (HuMCs). In a chronic house dust mite (HDM)-driven allergic airway inflammation mouse model, we observed that PDE3 deficiency or PDE3 inhibition (PDE3i) therapy reduced the numbers of epithelial MCs, when compared to control mice. Mouse bone marrow-derived MCs (bmMCs) and the human HMC1 and LAD2 cell lines predominantly expressed PDE3B and PDE4A. BmMCs from Pde3^−/− mice showed reduced loss of the degranulation marker CD107b compared with wild-type BmMCs, when stimulated in an immunoglobulin E (IgE)-dependent manner. Following both IgE-mediated and substance P-mediated activation, PDE3i-pretreated basophils, LAD2 cells, and HuMCs, showed less degranulation than diluent controls, as measured by surface CD63 expression. MCs lacking PDE3 or treated with the PDE3i enoximone exhibited a lower calcium flux upon stimulation with ionomycine. In conclusion PDE3 plays a critical role in basophil and mast cell degranulation and therefore its inhibition may be a treatment option in allergic disease.

Kinase inhibitors in the treatment of obstructive pulmonary diseases

Chronic pulmonary diseases, including chronic obstructive pulmonary disease (COPD) and asthma, are major causes of death and reduced quality of life. Characteristic of chronic pulmonary disease is excessive lung inflammation that occurs in response to exposure to inhaled irritants, chemicals, and allergens. Chronic inflammation leads to remodeling of the airways that includes excess mucus secretion, proliferation of smooth muscle cells, increased deposition of extracellular matrix proteins and fibrosis. Protein kinases have been implicated in mediating inflammatory signals and airway remodeling associated with reduced lung function in chronic pulmonary disease. This review will highlight the role of protein kinases in the lung during chronic inflammation and examine opportunities to use protein kinase inhibitors for the treatment of chronic pulmonary diseases.

Sesamol Alleviates Airway Hyperresponsiveness and Oxidative Stress in Asthmatic Mice

Sesamol, isolated from sesame seeds (Sesamum indicum), was previously shown to have antioxidative, anti-inflammatory, and anti-tumor effects. Sesamol also inhibited lipopolysaccharide (LPS)-induced pulmonary inflammatory response in rats. However, it remains unclear how sesamol regulates airway inflammation and oxidative stress in asthmatic mice. This study aimed to investigate the efficacy of sesamol on oxidative stress and airway inflammation in asthmatic mice and tracheal epithelial cells. BALB/c mice were sensitized with ovalbumin, and received oral sesamol on days 14 to 27. Furthermore, BEAS-2B human bronchial epithelial cells were treated with sesamol to investigate inflammatory cytokine levels and oxidative responses in vitro. Our results demonstrated that oral sesamol administration significantly suppressed eosinophil infiltration in the lung, airway hyperresponsiveness, and T helper 2 cell-associated (Th2) cytokine expressions in bronchoalveolar lavage fluid and the lungs. Sesamol also significantly increased glutathione expression and reduced malondialdehyde levels in the lungs of asthmatic mice. We also found that sesamol significantly reduced proinflammatory cytokine levels and eotaxin in inflammatory BEAS-2B cells. Moreover, sesamol alleviated reactive oxygen species formation, and suppressed intercellular cell adhesion molecule-1 (ICAM-1) expression, which reduced monocyte cell adherence. We demonstrated that sesamol showed potential as a therapeutic agent for improving asthma.

Airway epithelial ITGB4 deficiency in early life mediates pulmonary spontaneous inflammation and enhanced allergic immune response

Lung immune responses to respiratory pathogens and allergens are initiated in early life which will further influence the later onset of asthma. The airway epithelia form the first mechanical physical barrier to allergic stimuli and environmental pollutants, which is also the key regulator in the initiation and development of lung immune response. However, the epithelial regulation mechanisms of early-life lung immune responses are far from clear. Our previous study found that integrin β4 (ITGB4) is decreased in the airway epithelium of asthma patients with specific variant site. ITGB4 deficiency in adult mice aggravated the lung Th2 immune responses and enhanced airway hyper-responsiveness (AHR) with a house dust mite (HDM)-induced asthma model. However, the contribution of ITGB4 to the postnatal lung immune response is still obscure. Here, we further demonstrated that ITGB4 deficiency following birth mediates spontaneous lung inflammation with ILC2 activation and increased infiltration of eosinophils and lymphocytes. Moreover, ITGB4 deficiency regulated thymic stromal lymphopoietin (TSLP) production in airway epithelial cells through EGFR pathways. Neutralization of TSLP inhibited the spontaneous inflammation significantly in ITGB4-deficient mice. Furthermore, we also found that ITGB4 deficiency led to exaggerated lung allergic inflammation response to HDM stress. In all, these findings indicate that ITGB4 deficiency in early life causes spontaneous lung inflammation and induces exaggerated lung inflammation response to HDM aeroallergen.

Environmental Exposures and Asthma Development: Autophagy, Mitophagy, and Cellular Senescence

Environmental pollutants and allergens induce oxidative stress and mitochondrial dysfunction, leading to key features of allergic asthma. Dysregulations in autophagy, mitophagy, and cellular senescence have been associated with environmental pollutant and allergen-induced oxidative stress, mitochondrial dysfunction, secretion of multiple inflammatory proteins, and subsequently development of asthma. Particularly, particulate matter 2.5 (PM2.5) has been reported to induce autophagy in the bronchial epithelial cells through activation of AMP-activated protein kinase (AMPK), drive mitophagy through activating PTEN-induced kinase 1(PINK1)/Parkin pathway, and induce cell cycle arrest and senescence. Intriguingly, allergens, including ovalbumin (OVA), Alternaria alternata, and cockroach allergen, have also been shown to induce autophagy through activation of different signaling pathways. Additionally, mitochondrial dysfunction can induce cell senescence due to excessive ROS production, which affects airway diseases. Although autophagy and senescence share similar properties, recent studies suggest that autophagy can either accelerate the development of senescence or prevent senescence. Thus, in this review, we evaluated the literature regarding the basic cellular processes, including autophagy, mitophagy, and cellular senescence, explored their molecular mechanisms in the regulation of the initiation and downstream signaling. Especially, we highlighted their involvement in environmental pollutant/allergen-induced major phenotypic changes of asthma such as airway inflammation and remodeling and reviewed novel and critical research areas for future studies. Ultimately, understanding the regulatory mechanisms of autophagy, mitophagy, and cellular senescence may allow for the development of new therapeutic targets for asthma.

Wenshen decoction suppresses inflammation in IL-33-induced asthma murine model via inhibiting ILC2 activation

Background

Wenshen decoction, consisting of Epimedium brevicornu Maxim, Morinda officinalis How and Cnidium monnieri (L.) Cusson, has favorable efficacy in the treatment of asthma in China.

Methods

The present study investigated the potential immunomodulatory mechanism underlying the therapeutic effects of Wenshen decoction on mouse asthma.

Results

Oral Wenshen decoction could ameliorate the production of IL-4, IL-5, IL-13 in the bronchoalveolar lavage fluid (BALF), reduce serum IgE, and improve the airway hyperresponsiveness (AHR) and airway inflammation in the BALB/c mice after intranasal treatment with recombinant IL-33. Moreover, Wenshen decoction reduced ILC2 and RORα mRNA expression, decreased the mRNA expression of ICOS and ST2 in the lung, but significantly increased the production of IFN-γ.

Conclusions

Our study indicates that Wenshen decoction may inhibit the activation of ILC2 through the IL-33/ST2/ICOS pathway to further suppress airway inflammation and AHR in the asthmatic mice, and the increased IFN-γ might be related to the effects of Wenshen decoction on ILC2.

Supplementary prevention and management of asthma with quercetin phytosome: a pilot registry

BACKGROUND

In association with standard management, natural pharmaceutical standard (PS) supplements may play an important role in managing and preventing mild-to-moderate symptoms of asthma, a significant health issue that impacts patients and the healthcare system. Quercetin is a natural flavonoid with important biological properties (anti-inflammatory, antihistamine and anti-oxidative actions).

METHODS

In this pilot registry, we evaluated the effects of quercetin formulated with the Phytosome® delivery system (Quercefit™, QFit)+standard management (SM) in otherwise healthy subjects with mild-moderate asthmatic attacks and rhinitis. Subjects used either QFit 1 or 2 tabs/day in association with SM or SM only (control group). After 30 days of management, we evaluated the presence of the main signs/symptoms of asthma according to the GINA classification system also considering the need of rescue medication, nasal drops, the use of inhalers, the rhinitis score and oxidative stress.

RESULTS

QFit+SM showed superior results compared with SM alone in controlling, preventing and reducing daily and night symptoms, in maintaining higher peak expiratory flow (PEF) and in decreasing PEF variability. The supplementary use of QFit improved additional measures of asthma management, decreasing the use of inhalers, nasal drops, rescue medications and improving the rhinitis score. QFit produced a significantly more evident reduction in oxidative stress compared with SM; Qfit showed a very good safety profile.

CONCLUSIONS

This preliminary supplement, concept registry shows a potential protective and preventive effect of quercetin on attacks frequency and in controlling the most common signs/symptoms of asthma in the milder cases of the disease.

Fangxiao Formula alleviates airway inflammation and remodeling in rats with asthma via suppression of transforming growth factor-β/Smad3 signaling pathway

Asthma is a common obstructive airway disease characterized by inflammation and remodeling with a progressive decline in lung function. Fangxiao Formula (FXF) is an herbal medicine that has achieved significant clinical benefits toward asthma patients, but the relevant mechanism has not yet been clarified. The aim of this study was to determine the inhibitory effects of FXF on airway inflammation and remodeling, and investigate the activities of TGF‑β/Smads signaling pathway in the rat asthma model. Rats were sensitized by ovalbumin (OVA) for six weeks to establish the asthma experimental model. OVA-challenged animals were randomly divided into 5 groups and received different concentrations of FXF or dexamethasone. The animals in blank control group received saline only. Lung tissues were collected and analyzed for determining the inflammatory cells infiltration, HE and PAS staining, airway wall thickness and collagen deposition. The productions of inflammatory cytokine productions were analyzed by ELISA in the bronchoalveolar lavage (BAL) fluid. Immunohistochemical analysis was performed to measure the expression of α-SMA and PCNA in lung tissue after the treatment of FXF. The levels of TGF-β were assessed by both immunohistology and western blotting, and the expression of p-Smad2/3 proteins were determined by western blotting analysis. Our results indicated that FXF attenuated the infiltration of inflammatory cells, decreased the production of Th2 cytokines and simultaneously increased the levels of Th1 cytokine in the asthma rat model. In addition, FXF reduced allergen-induced increased airway wall thickness, goblet cell hyperplasia and collagen deposition. Furthermore, the expression levels of TGF-β and p-Smad3 were obviously reduced after the treatment of FXF. These results indicate that FXF alleviates airway inflammation and remodeling by restoring the balance of Th1/Th2 cytokines and the TGF-β/Smad-3 pathway, therefor providing potential therapeutic approach for asthmatic patients.

MIF signaling blocking alleviates airway inflammation and airway epithelial barrier disruption in a HDM-induced asthma model

Recent studies have indicated that Macrophage migration inhibitory factor (MIF) plays an important role in the prevention and treatment of asthma. However the role of MIF in airway inflammation and airway epithelial barrier disruption in house dust mite (HDM)-induced asthma has not been addressed. We hypothesized that MIF contributed to HDM-induced the production of Th2-associated cytokines and E-cadherin dysfunction in asthmatic mice and 16HBE cells. In vivo, a HDM-induced asthma mouse model was set up and mice treated with MIF antagonist ISO-1 after HDM. The mice treated with the ISO-1 ameliorated airway hyper-reactivity, airway inflammation, increased serum IgE levels, the aberrant arrangement of E-cadherin as well as the release of Th2 cytokines induced by HDM. In vitro, the exposure of 16HBE cells to HDM and rhMIF resulted in airway epithelial barrier disruption, inflammatory cytokine production and enhanced glycolytic flux. While these changes were attenuated by MIF siRNA treatment. Sequentially, treatment of 16HBE cells with PFKFB3 antagonist PFK15 significantly lowered rhMIF-induced these changes in 16HBE cells. Therefore, these results indicate that MIF may be an important contributor in airway inflammation and airway epithelial barrier disruption of HDM-induced asthma. Moreover, HDM specifically induces airway inflammation and airway epithelial barrier disruption of 16HBE cells through MIF-mediated enhancement of aerobic glycolysis.

Mast Cell-Mediated Orchestration of the Immune Responses in Human Allergic Asthma: Current Insights

Improving the lung function after experimental allergen challenge by blocking of mast cell (MC) mediators and the capability of MC mediators (including histamine, prostaglandin (PG) D2, and leukotriene (LT) C4) in induction of mucosal edema, bronchoconstriction, and mucus secretion provide evidence that MCs play a key role in pathophysiology of asthma. In asthma, the number of MCs increases in the airways and infiltration of MCs in a variety of anatomical sites including the epithelium, the submucosal glands, and the smooth muscle bundles occurs. MC localization within the ASM is accompanied with the hypertrophy and hyperplasia of the layer, and smooth muscle dysfunction that is mainly observed in forms of bronchial hyperresponsiveness, and variable airflow obstruction. Owing to the expression of a wide range of surface receptors and releasing various cytoplasmic mediators, MCs orchestrate the pathologic events of the disease. MC-released preformed mediators including chymase, tryptase, and histamine and de novo synthesized mediators such as PGD2, LTC4, and LTE4 in addition of cytokines mainly TGFβ1, TSLP, IL-33, IL-4, and IL-13 participate in pathogenesis of asthma. The release of MC mediators and MC/airway cell interactions during remodeling phase of asthma results in persistent cellular and structural changes in the airway wall mainly epithelial cell shedding, goblet cell hyperplasia, hypertrophy of ASM bundles, fibrosis in subepithelial region, abnormal deposition of extracellular matrix (ECM), increased tissue vascularity, and basement membrane thickening. We will review the current knowledge regarding the participation of MCs in each stage of asthma pathophysiology including the releasing mediators and their mechanism of action, expression of receptors by which they respond to stimuli, and finally the pharmaceutical products designed based on the strategy of blocking MC activation and mediator release.

Protective Effects of Licochalcone A Improve Airway Hyper-Responsiveness and Oxidative Stress in a Mouse Model of Asthma

Licochalcone A was isolated from Glycyrrhiza uralensis and previously reported to have antitumor and anti-inflammatory effects. Licochalcone A has also been found to inhibit the levels of Th2-associated cytokines in the bronchoalveolar lavage fluid (BALF) of asthmatic mice. However, the molecular mechanism underlying airway inflammation and how licochalcone A regulates oxidative stress in asthmatic mice are elusive. In this study, we investigated whether licochalcone A could attenuate inflammatory and oxidative responses in tracheal epithelial cells, and whether it could ameliorate oxidative stress and airway inflammation in asthmatic mice. Inflammatory human tracheal epithelial (BEAS-2B) cells were treated with licochalcone A to evaluate oxidative responses and inflammatory cytokine levels. In addition, BALB/c mice were sensitized with ovalbumin (OVA) and injected intraperitoneally with licochalcone A (5 or 10 mg/kg). Licochalcone A significantly inhibited reactive oxygen species, eotaxin, and proinflammatory cytokines in BEAS-2B cells. Licochalcone A also decreased intercellular adhesion molecule 1 levels in inflammatory BEAS-2B cells, blocking monocyte cell adherence. We also found that licochalcone A significantly decreased oxidative responses, reduced malondialdehyde levels, and increased glutathione levels in the lungs of OVA-sensitized mice. Furthermore, licochalcone A decreased airway hyper-responsiveness, eosinophil infiltration, and Th2 cytokine production in the BALF. These findings suggest that licochalcone A alleviates oxidative stress, inflammation, and pathological changes by inhibiting Th2-associated cytokines in asthmatic mice and human tracheal epithelial cells. Thus, licochalcone A demonstrated therapeutic potential for improving asthma.

500 Million Alveoli from 30,000 Feet: A Brief Primer on Lung Anatomy

The lungs are a complex organ that fulfill multiple life-sustaining roles including transfer of oxygen and carbon dioxide between the ambient environment and the bloodstream, host defense, and immune homeostasis. As in any biological system, an understanding of the underlying anatomy is prerequisite for successful experimental design and appropriate interpretation of data, regardless of the precise experimental model or procedure in use. This chapter provides an overview of human lung anatomy focused on the airways, the ultrastructure or parenchyma of the lung, the pulmonary vasculature, the innervation of the lungs, and the pulmonary lymphatic system. We will also discuss notable anatomic differences between mouse and human lungs.

The Role of Autophagy in Eosinophilic Airway Inflammation

Autophagy is a homeostatic mechanism that discards not only invading pathogens but also damaged organelles and denatured proteins via lysosomal degradation. Increasing evidence suggests a role for autophagy in inflammatory diseases, including infectious diseases, Crohn's disease, cystic fibrosis, and pulmonary hypertension. These studies suggest that modulating autophagy could be a novel therapeutic option for inflammatory diseases. Eosinophils are a major type of inflammatory cell that aggravates airway inflammatory diseases, particularly corticosteroid-resistant inflammation. The eosinophil count is a useful tool for assessing which patients may benefit from inhaled corticosteroid therapy. Recent studies demonstrate that autophagy plays a role in eosinophilic airway inflammatory diseases by promoting airway remodeling and loss of function. Genetic variant in the autophagy gene ATG5 is associated with asthma pathogenesis, and autophagy regulates apoptotic pathways in epithelial cells in individuals with chronic obstructive pulmonary disease. Moreover, autophagy dysfunction leads to severe inflammation, especially eosinophilic inflammation, in chronic rhinosinusitis. However, the mechanism underlying autophagy-mediated regulation of eosinophilic airway inflammation remains unclear. The aim of this review is to provide a general overview of the role of autophagy in eosinophilic airway inflammation. We also suggest that autophagy may be a new therapeutic target for airway inflammation, including that mediated by eosinophils.

Dynamics of helper CD4 T cells during acute and stable allergic asthma

Asthma comprises heterogeneous clinical subtypes driven by diverse pathophysiological mechanisms. We characterized the modulation of the inflammatory environment with the phenotype, gene expression, and function of helper CD4 T cells among acutely exacerbated and stable asthma patients. Systemic Th2 immune deviation (IgE and Th2 cytokines) and inflammation (IL-6, CRP) were associated with increased Th17 cells during acute asthma. Th2/Th17 cell differentiation during acute asthma was regulated by the enhanced expression of transcription factors (c-MAF, IRF-4). The development of pathogenic Th2 cells during acute asthma was characterized by the secretion of inflammatory cytokines coupled with Th2 molecules and PPARγ expression. The acquisition of CD15S, CD39, CD101, and CCR4 contributed to the increased heterogeneity of Regulatory T cells during asthma. Two clusters were derived from above cytokines, CD4 T cell phenotypes, and clinical data. Cluster 1, characterized by high eosinophils, Th2 and ILC2 frequencies, and higher exacerbation rates, may represent Th2-high subtype. Cluster 2 represents a more complex subtype; it is constituted by higher neutrophils or Th17 frequencies, higher inhaled corticosteroids dose and poor asthma control. In conclusion, we characterized systematically and longitudinally Th2-high and non-Th2 asthma subtypes and the heterogeneity of CD4 T cells in stable and acute asthma.

Targeting the interleukin-4 and interleukin-13 pathways in severe asthma: current knowledge and future needs

PURPOSE OF REVIEW

Severe asthma is a heterogeneous disease that can be classified into phenotypes and endotypes based upon clinical or biological characteristics. Interleukin (IL)-4 and IL-13 play a key role in type 2 (T2) asthma. This article reviews the signaling pathway of IL-4 and IL-13 and highlights its targeted therapy in severe asthma.

RECENT FINDINGS

Several clinical trials of biologics targeting the IL-4/IL-13 pathway have recently been completed. In patients with severe, uncontrolled asthma, targeting IL-13 alone with biologics including lebrikizumab and tralokinumab has not shown consistent reduction in asthma exacerbations. Simultaneous targeting of both IL-4 and IL-13 by blocking IL-4 receptor α using dupilumab has yielded more consistent results in reducing asthma exacerbations and improving lung function, especially in patients with increased blood eosinophils. Other biomarkers of T2 inflammation such as exhaled nitric oxide and serum periostin may also predict response to biologics targeting the IL-4/IL-13 pathway.

SUMMARY

No biologic targeting the IL-4/IL-13 pathway is currently available for treatment of asthma, but emerging data suggest that biologics targeting IL-4 and IL-13 together may benefit patients with T2 high asthma. Additional data are needed about long-term efficacy and safety prior to incorporating these drugs into routine clinical practice.

Biological effects of airborne fine particulate matter (PM2.5) exposure on pulmonary immune system

Airborne fine particulate matter (PM_2.5) attracts more and more attention due to its environmental effects. The immune system appears to be a most sensitive target organ for the environmental pollutants. Inhaled PM_2.5 can deposit in different compartments in the respiratory tract and interact with epithelial cells and resident immune cells. Exposed to PM_2.5 can induce local or systematic inflammatory responses. This review focus on the effects of respiratory tract exposed to PM_2.5. Firstly, we introduced the major emission sources, basic characteristics of PM_2.5 and discussed its immunoadjuvant potential. Secondly, we elaborated the immune cells in the respiratory tract and the deposition of PM_2.5 regarding the structural characteristics of the respiratory tract. Furthermore, we summarized the in vivo/vitro studies that revealed the immunotoxic effects of PM_2.5 exposure to pulmonary cellular effectors and explored the contribution of PM_2.5 exposure to the Th1/Th2 balance.

Inflammatory and Oxidative Stress Markers in Experimental Allergic Asthma

Ovalbumin-induced allergic lung inflammation (ALI) is a condition believed to be mediated by cytokines, extracellular matrix remodeling, and redox imbalance. In this study, we evaluated pulmonary function together with inflammatory markers as interleukin-4 (IL-4), myeloperoxidase (MPO), eosinophil cells, and redox markers in the lungs of BALB/c mice after ovalbumin (OVA) sensitization and challenge. Our results showed an increase in bronchial hyperresponsiveness stimulated by methacholine (Mch), inflammatory cell influx, especially eosinophils together with an increase of high mobility group box 1 (HMGB1) and altered lipid peroxidation (LP) and antioxidant defenses in the OVA group compared to the control group (p ≤ 0.5). Thus, we demonstrated that OVA-induced ALI altered redox status concomitantly with impaired lung function, which was associated with HMGB1 expression and proteolytic remodeling. Taken together all results found here, we may suggest HMGB1 is an important therapeutic target for asthma, once orchestrates the redox signaling, inflammation, and remodeling that contribute to the disease development.

Role of epithelial chemokines in the pathogenesis of airway inflammation in asthma (Review)

As the first barrier to the outside environment, airway epithelial cells serve a central role in the initiation and development of airway inflammation. Chemokines are the most direct and immediate cell factors for the recruitment and migration of inflammatory cells. The present review focused on the role of epithelial chemokines in the pathogenesis of airway inflammation in asthma. In addition to traditional CC family chemokines and CXC family chemokines, airway epithelial cells also express other chemokines, including thymic stromal lymphopoietin and interleukin‑33. By expressing and secreting chemokines, airway epithelial cells serve a key role in orchestrating airway inflammation in asthma.

Nordic consensus statement on the systematic assessment and management of possible severe asthma in adults

Although a minority of asthma patients suffer from severe asthma, they represent a major clinical challenge in terms of poor symptom control despite high-dose treatment, risk of exacerbations, and side effects. Novel biological treatments may benefit patients with severe asthma, but are expensive, and are only effective in appropriately targeted patients. In some patients, symptoms are driven by other factors than asthma, and all patients with suspected severe asthma ('difficult asthma') should undergo systematic assessment, in order to differentiate between true severe asthma, and 'difficult-to-treat' patients, in whom poor control is related to factors such as poor adherence or co-morbidities. The Nordic Consensus Statement on severe asthma was developed by the Nordic Severe Asthma Network, consisting of members from Norway, Sweden, Finland, Denmark, Iceland and Estonia, including representatives from the respective national respiratory scientific societies with the aim to provide an overview and recommendations regarding the diagnosis, systematic assessment and management of severe asthma. Furthermore, the Consensus Statement proposes recommendations for the organization of severe asthma management in primary, secondary, and tertiary care.

ITGB4 is essential for containing HDM-induced airway inflammation and airway hyperresponsiveness

Airway epithelial cells play a significant role in the pathogenesis of asthma. Although the structural and functional defects of airway epithelial cells have been postulated to increase asthma susceptibility and exacerbate asthma severity, the mechanism and implication of these defects remain uncertain. Integrin β4 (ITGB4) is a structural adhesion molecule that is downregulated in the airway epithelium of asthma patients. In this study, we demonstrated that ITGB4 deficiency leads to severe allergy-induced airway inflammation and airway hyper-responsiveness (AHR) in mice. After house dust mite (HDM) challenge, epithelial cell-specific ITGB4-deleted mice showed increased lymphocyte, eosinophil, and neutrophil infiltration into lung compared with that of the wild-type mice. ITGB4 deficiency also resulted in increased expression of the Th2 cytokine IL-4, IL-13, and the Th17 cytokine IL-17A in the lung tissue and in the T cells after HDM challenge. The aggravated inflammation in ITGB4 defect mice was partly caused by enhanced disrupted epithelial barrier integrity after HDM stress, which induced the increased thymic stromal lymphopoietin secretion from airway epithelial cells. This study therefore demonstrates that ITGB4 plays a pivotal role in containing allergen-mediated lung inflammation and airway hyper-responsiveness in allergic asthma.

A pathophysiological role of PDE3 in allergic airway inflammation

Phosphodiesterase 3 (PDE3) and PDE4 regulate levels of cyclic AMP, which are critical in various cell types involved in allergic airway inflammation. Although PDE4 inhibition attenuates allergic airway inflammation, reported side effects preclude its application as an antiasthma drug in humans. Case reports showed that enoximone, which is a smooth muscle relaxant that inhibits PDE3, is beneficial and lifesaving in status asthmaticus and is well tolerated. However, clinical observations also showed antiinflammatory effects of PDE3 inhibition. In this study, we investigated the role of PDE3 in a house dust mite-driven (HDM-driven) allergic airway inflammation (AAI) model that is characterized by T helper 2 cell activation, eosinophilia, and reduced mucosal barrier function. Compared with wild-type (WT) littermates, mice with a targeted deletion of the PDE3A or PDE3B gene showed significantly reduced HDM-driven AAI. Therapeutic intervention in WT mice showed that all hallmarks of HDM-driven AAI were abrogated by the PDE3 inhibitors enoximone and milrinone. Importantly, we found that enoximone also reduced the upregulation of the CD11b integrin on mouse and human eosinophils in vitro, which is crucial for their recruitment during allergic inflammation. This study provides evidence for a hitherto unknown antiinflammatory role of PDE3 inhibition in allergic airway inflammation and offers a potentially novel treatment approach.

Tomatidine Attenuates Airway Hyperresponsiveness and Inflammation by Suppressing Th2 Cytokines in a Mouse Model of Asthma

Tomatidine is isolated from the fruits of tomato plants and found to have anti-inflammatory effects in macrophages. In the present study, we investigated whether tomatidine suppresses airway hyperresponsiveness (AHR) and eosinophil infiltration in asthmatic mice. BALB/c mice were sensitized with ovalbumin and treated with tomatidine by intraperitoneal injection. Airway resistance was measured by intubation analysis as an indication of airway responsiveness, and histological studies were performed to evaluate eosinophil infiltration in lung tissue. Tomatidine reduced AHR and decreased eosinophil infiltration in the lungs of asthmatic mice. Tomatidine suppressed Th2 cytokine production in bronchoalveolar lavage fluid. Tomatidine also blocked the expression of inflammatory and Th2 cytokine genes in lung tissue. In vitro, tomatidine inhibited proinflammatory cytokines and CCL11 production in inflammatory BEAS-2B bronchial epithelial cells. These results indicate that tomatidine contributes to the amelioration of AHR and eosinophil infiltration by blocking the inflammatory response and Th2 cell activity in asthmatic mice.

Phloretin Attenuates Allergic Airway Inflammation and Oxidative Stress in Asthmatic Mice

Phloretin (PT), isolated from the apple tree, was previously demonstrated to have antioxidative and anti-inflammatory effects in macrophages and anti-adiposity effects in adipocytes. Inflammatory immune cells generate high levels of reactive oxygen species (ROS) for stimulated severe airway hyperresponsiveness (AHR) and airway inflammation. In this study, we investigated whether PT could reduce oxidative stress, airway inflammation, and eosinophil infiltration in asthmatic mice, and ameliorate oxidative and inflammatory responses in tracheal epithelial cells. BALB/c mice were sensitized with ovalbumin (OVA) to induce asthma symptoms. Mice were randomly assigned to the five experimental groups: normal controls; OVA-induced asthmatic mice; and OVA-induced mice injected intraperitoneally with one of the three PT doses (5, 10, or 20 mg/kg). In addition, we treated inflammatory human tracheal epithelial cells (BEAS-2B cells) with PT to assess oxidative responses and the levels of proinflammatory cytokines and chemokines. We found that PT significantly reduced goblet cell hyperplasia and eosinophil infiltration, which decreased AHR, inflammation, and oxidative responses in the lungs of OVA-sensitized mice. PT also decreased malondialdehyde levels in the lung and reduced Th2 cytokine production in bronchoalveolar lavage fluids. Furthermore, PT reduced ROS, proinflammatory cytokines, and eotaxin production in BEAS-2B cells. PT also suppressed monocyte cell adherence to inflammatory BEAS-2B cells. These findings suggested that PT alleviated pathological changes, inflammation, and oxidative stress by inhibiting Th2 cytokine production in asthmatic mice. PT showed therapeutic potential for ameliorating asthma symptoms in the future.

Dupilumab for the treatment of asthma

INTRODUCTION

Dupilumab (REGN668/SAR231893), produced by a collaboration between Regeneron and Sanofi, is a monoclonal antibody currently in phase III for moderate-to-severe asthma. Dupilumab is directed against the α-subunit of the interleukin (IL)-4 receptor and blocks the IL-4 and IL-13 signal transduction. Areas covered: Pathophysiological role of IL-4 and IL-13 in asthma; mechanism of action of dupilumab; pharmacology of IL-4 receptor; phase I and phase II studies with dupilumab; regulatory affairs. Expert opinion: Patients with severe asthma who are not sufficiently controlled with standard-of-care represent the target asthma population for dupilumab. If confirmed, efficacy of dupilumab in both eosinophilic and non-eosinophilic severe asthma phenotype might represent an advantage over approved biologics for asthma, including omalizumab, mepolizumab, and reslizumab. Head-to-head studies to compare dupilumab versus other biologics with different mechanism of action are required. Pediatric studies with dupilumab are currently lacking and should be undertaken to assess efficacy and safety of this drug in children with severe asthma. The lack of preclinical data and published results of the completed four phase I studies precludes a complete assessment of the pharmacological profile of dupilumab. Dupilumab seems to be generally well tolerated, but large studies are required to establish its long-term safety and tolerability.