IFN-gamma, IL-4 and IL-13 modulate responsiveness of human airway smooth muscle cells to IL-13

Leptin augments IL-13-induced airway eotaxins and submucosal eosinophilia in obesity-associated asthma

BACKGROUND

Airway tissue eosinophilia can be an observed feature of obesity-associated type 2 (T2) asthma, but the processes mediating this inflammation are unknown.

OBJECTIVE

To investigate a process whereby leptin, an adipokine elevated in obesity, potentiates pulmonary eosinophilia and eotaxin production by airway fibroblasts in T2 asthma.

METHODS

We assessed associations between body mass index and airway eosinophilia as well as leptin and eotaxin production in 78 participants with asthma, 36 of whom exhibited obesity. Cultured human airway fibroblasts and mouse models of chronic allergic airway disease were used to evaluate leptin's effect on eotaxin production and lung eosinophilia. The role of IL-13 receptor alpha 2 (IL-13Rα2) in mediating these processes was examined using specific neutralizing antibodies in vitro.

RESULTS

In participants with T2 asthma and obesity, we observed that airway tissue eosinophilia did not associate with traditional T2 inflammation metrics such as peripheral and/or bronchoalveolar lavage fluid eosinophil counts or with fractional exhaled nitric oxide. Alternatively, we observed elevated bronchoalveolar lavage fluid leptin and eotaxin-1 levels. In airway fibroblasts from participants with asthma, leptin augmented IL-13-induced eotaxin-1 and eotaxin-3 production and IL13RA2 expression. In mice, elevated leptin promoted airway IL-13Rα2 and eotaxin production by lung fibroblasts and lung tissue eosinophilia following chronic house dust mite allergen exposure. Inhibition of IL-13Rα2 reduced combined leptin and IL-13-stimulated eotaxin secretion by human airway fibroblasts.

CONCLUSIONS

We identified a potential association explaining airway tissue eosinophil retention in obesity-associated T2 asthma through leptin-mediated enhancement of IL-13-induced eosinophil chemokine production by airway fibroblasts, a process requiring IL-13Rα2.

Determining the toxicological effects of indoor air pollution on both a healthy and an inflammatory-comprised model of the alveolar epithelial barrier in vitro

Exposure to indoor air pollutants (IAP) has increased recently, with people spending more time indoors (i.e. homes, offices, schools and transportation). Increased exposures of IAP on a healthy population are poorly understood, and those with allergic respiratory conditions even less so. The objective of this study, therefore, was to implement a well-characterised in vitro model of the human alveolar epithelial barrier (A549 + PMA differentiated THP-1 incubated with and without IL-13, IL-5 and IL-4) to determine the effects of a standardised indoor particulate (NIST 2583) on both a healthy lung model and one modelling a type-II (stimulated with IL-13, IL-5 and IL-4) inflammatory response (such as asthma).Using concentrations from the literature, and an environmentally appropriate exposure we investigated 232, 464 and 608ng/cm2 of NIST 2583 respectively. Membrane integrity (blue dextran), viability (trypan blue), genotoxicity (micronucleus (Mn) assay) and (pro-)/(anti-)inflammatory effects (IL-6, IL-8, IL-33, IL-10) were then assessed 24 h post exposure to both models. Models were exposed using a physiologically relevant aerosolisation method (VitroCell Cloud 12 exposure system).No changes in Mn frequency or membrane integrity in either model were noted when exposed to any of the tested concentrations of NIST 2583. A significant decrease (p < 0.05) in cell viability at the highest concentration was observed in the healthy model. Whilst cell viability in the "inflamed" model was decreased at the lower concentrations (significantly (p < 0.05) after 464ng/cm2). A significant reduction (p < 0.05) in IL-10 and a significant increase in IL-33 was seen after 24 h exposure to NIST 2583 (464, 608ng/cm2) in the "inflamed" model.Collectively, the results indicate the potential for IAP to cause the onset of a type II response as well as exacerbating pre-existing allergic conditions. Furthermore, the data imposes the importance of considering unhealthy individuals when investigating the potential health effects of IAP. It also highlights that even in a healthy population these particles have the potential to induce this type II response and initiate an immune response following exposure to IAP.

Epithelial-Mesenchymal Transition Mechanisms in Chronic Airway Diseases: A Common Process to Target?

Epithelial-to-mesenchymal transition (EMT) is a reversible process, in which epithelial cells lose their epithelial traits and acquire a mesenchymal phenotype. This transformation has been described in different lung diseases, such as lung cancer, interstitial lung diseases, asthma, chronic obstructive pulmonary disease and other muco-obstructive lung diseases, such as cystic fibrosis and non-cystic fibrosis bronchiectasis. The exaggerated chronic inflammation typical of these pulmonary diseases can induce molecular reprogramming with subsequent self-sustaining aberrant and excessive profibrotic tissue repair. Over time this process leads to structural changes with progressive organ dysfunction and lung function impairment. Although having common signalling pathways, specific triggers and regulation mechanisms might be present in each disease. This review aims to describe the various mechanisms associated with fibrotic changes and airway remodelling involved in chronic airway diseases. Having better knowledge of the mechanisms underlying the EMT process may help us to identify specific targets and thus lead to the development of novel therapeutic strategies to prevent or limit the onset of irreversible structural changes.

New insights into the pathophysiology and therapeutic targets of asthma and comorbid chronic rhinosinusitis with or without nasal polyposis

Asthma and chronic rhinosinusitis with nasal polyps (CRSwNP) or without (CRSsNP) are chronic respiratory diseases. These two disorders often co-exist based on common anatomical, immunological, histopathological, and pathophysiological basis. Usually, asthma with comorbid CRSwNP is driven by type 2 (T2) inflammation which predisposes to more severe, often intractable, disease. In the past two decades, innovative technologies and detection techniques in combination with newly introduced targeted therapies helped shape our understanding of the immunological pathways underlying inflammatory airway diseases and to further identify several distinct clinical and inflammatory subsets to enhance the development of more effective personalized treatments. Presently, a number of targeted biologics has shown clinical efficacy in patients with refractory T2 airway inflammation, including anti-IgE (omalizumab), anti-IL-5 (mepolizumab, reslizumab)/anti-IL5R (benralizumab), anti-IL-4R-α (anti-IL-4/IL-13, dupilumab), and anti-TSLP (tezepelumab). In non-type-2 endotypes, no targeted biologics have consistently shown clinical efficacy so far. Presently, multiple therapeutical targets are being explored including cytokines, membrane molecules and intracellular signalling pathways to further expand current treatment options for severe asthma with and without comorbid CRSwNP. In this review, we discuss existing biologics, those under development and share some views on new horizons.

From Beneath the Skin to the Airway Wall: Understanding the Pathological Role of Adipose Tissue in Comorbid Asthma-Obesity

This article provides a contemporary report on the role of adipose tissue in respiratory dysfunction. Adipose tissue is distributed throughout the body, accumulating beneath the skin (subcutaneous), around organs (visceral), and importantly in the context of respiratory disease, has recently been shown to accumulate within the airway wall: "airway-associated adipose tissue." Excessive adipose tissue deposition compromises respiratory function and increases the severity of diseases such as asthma. The mechanisms of respiratory impairment are inflammatory, structural, and mechanical in nature, vary depending on the anatomical site of deposition and adipose tissue subtype, and likely contribute to different phenotypes of comorbid asthma-obesity. An understanding of adipose tissue-driven pathophysiology provides an opportunity for diagnostic advancement and patient-specific treatment. As an exemplar, the potential impact of airway-associated adipose tissue is highlighted, and how this may change the management of a patient with asthma who is also obese. © 2023 American Physiological Society. Compr Physiol 13:4321-4353, 2023.

Airway remodeling heterogeneity in asthma and its relationship to disease outcomes

Asthma affects an estimated 262 million people worldwide and caused over 461,000 deaths in 2019. The disease is characterized by chronic airway inflammation, reversible bronchoconstriction, and airway remodeling. Longitudinal studies have shown that current treatments for asthma (inhaled bronchodilators and corticosteroids) can reduce the frequency of exacerbations, but do not modify disease outcomes over time. Further, longitudinal studies in children to adulthood have shown that these treatments do not improve asthma severity or fixed airflow obstruction over time. In asthma, fixed airflow obstruction is caused by remodeling of the airway wall, but such airway remodeling also significantly contributes to airway closure during bronchoconstriction in acute asthmatic episodes. The goal of the current review is to understand what is known about the heterogeneity of airway remodeling in asthma and how this contributes to the disease process. We provide an overview of the existing knowledge on airway remodeling features observed in asthma, including loss of epithelial integrity, mucous cell metaplasia, extracellular matrix remodeling in both the airways and vessels, angiogenesis, and increased smooth muscle mass. While such studies have provided extensive knowledge on different aspects of airway remodeling, they have relied on biopsy sampling or pathological assessment of lungs from fatal asthma patients, which have limitations for understanding airway heterogeneity and the entire asthma syndrome. To further understand the heterogeneity of airway remodeling in asthma, we highlight the potential of in vivo imaging tools such as computed tomography and magnetic resonance imaging. Such volumetric imaging tools provide the opportunity to assess the heterogeneity of airway remodeling within the whole lung and have led to the novel identification of heterogenous gas trapping and mucus plugging as important predictors of patient outcomes. Lastly, we summarize the current knowledge of modification of airway remodeling with available asthma therapeutics to highlight the need for future studies that use in vivo imaging tools to assess airway remodeling outcomes.

Cavin-1 promotes M2 macrophages/microglia polarization via SOCS3

PURPOSE

Our study aimed to investigate the function of Cavin-1 and SOCS3 in macrophages/microglia M2 polarization and further explored the relevant mechanism.

METHODS

Expression levels of Cavin-1 and SOCS3 in macrophages/microglia were measured by western blotting and RT-PCR, respectively. Then, Cavin-1 or SOCS3 was gene silenced by a siRNA approach, and gene silencing efficiency was determined by western blotting. Next, co-immunoprecipitation (Co-IP) was employed to further analyze the interaction between Cavin-1 and SOCS3. Finally, the activation of STAT6/PPAR-γ signaling was evaluated using western blotting, and the M2 macrophages/microglia polarization was validated by measuring the mRNA expression of M2 markers by RT-PCR.

RESULTS

In the polarization process of macrophages/microglia to M2 phenotype, both Cavin-1 and SOCS3 increased synchronously at protein and mRNA level, reached the peak at the 6 h, and then decreased. After Cavin-1 or SOCS3 silencing, the expression of Cavin-1 and SOCS3 declined. These results suggested that Cavin-1 and SOCS3 were positively correlated in macrophages/microglia, and this conjecture was verified by Co-IP. Besides, Cavin-1 silencing not only suppressed the activation of STAT6/PPAR-γ pathway, but also suppressed the release of anti-inflammatory factors. Finally, we found that SOCS3 overexpression reversed the inhibitory effect of Cavin-1 silencing on the release of anti-inflammatory factors in M2 macrophages/microglia.

CONCLUSIONS

Cavin-1 and SOCS3 are actively involved in the process of M2 macrophages/microglia polarization. As a SOCS3 interacting protein, Cavin-1 can promote M2 macrophages/microglia polarization via SOCS3.

Repeated exposure of house dust mite induces progressive airway inflammation in mice: Differential roles of CCL17 and IL-13

We conducted a systematic evaluation of lung inflammation indued by repeated intranasal exposure (for 10 consecutive days) to a human aeroallergen, house dust mite (HDM) in BALB/c mice. Peak influx of neutrophils, monocytes/lymphocytes, and eosinophils was observed in bronchoalveolar lavage (BAL) on days 1, 7 and 11, respectively, and normalized to baseline by day 21. Peak elevations of Th2, myeloid-derived cytokines/chemokines and serum IgE were seen both in BAL and lung tissue homogenates between days 7 and 11, and declined thereafter; however, IL-33 levels remained elevated from day 7 to day 21. Airway hyperreactivity to inhaled methacholine was significantly increased by day 11 and decreased to baseline by day 21. The lung tissue showed perivascular and peribronchial cuffing, epithelial hypertrophy and hyperplasia and goblet cell formation in airways by day 11, and resolution by day 21. Levels of soluble collagen and tissue inhibitors of metalloproteinases (TIMP) also increased reflecting tissue remodeling in the lung. Microarray analysis demonstrated a significant time-dependent up-regulation of several genes including IL-33, CLCA3, CCL17, CD4, CD10, CD27, IL-13, Foxa3, IL-4, IL-10, and CD19, in BAL cells as well as the lung. Pre-treatment of HDM challenged mice with CCL17 and IL-13 antibodies reduced BAL cellularity, airway hyper-responsiveness (AHR), and histopathological changes. Notably, anti-IL-13, but not anti-CCL17 monoclonal antibodies (mAbs) reduced BAL neutrophilia while both mAbs attenuated eosinophilia. These results suggest that CCL17 has an overlapping, yet distinct profile versus IL-13 in the HDM model of pulmonary inflammation and potential for CCL17-based therapeutics in treating Th2 inflammation.

The Clusters of Transcription Factors NFATC2, STAT5, GATA2, AP1, RUNX1 and EGR2 Binding Sites at the Induced Il13 Enhancers Mediate Il13 Gene Transcription in Response to Antigenic Stimulation

IL-13 plays a critical role in mediating many biological processes responsible for allergic inflammation. Mast cells express Il13 mRNA and produce IL-13 protein in response to antigenic stimulation. Enhancers are essential in promoting gene transcription and are thought to activate transcription by delivering essential accessory cofactors to the promoter to potentiate gene transcription. However, enhancers mediating Il13 have not been identified. Furthermore, which Il13 enhancers detect signals triggered by antigenic stimulation have not yet been defined. In this study, we identified potential mouse Il13 enhancers using histone modification monomethylation at lysine residue 4 on histone 3 (H3K4me1) chromatin immunoprecipitation sequencing and acetylation at lysine residue 27 on histone 3 (H3K27ac) chromatin immunoprecipitation sequencing. We used Omni-assay for transposase-accessible chromatin sequencing to determine which accessible regions within the potential Il13 enhancers that responded to IgE receptor crosslinking. We also demonstrated that the transcription factor cluster consisting of the NFATC2, STAT5, GATA2, AP1, and RUNX1 binding sites at the proximal Il13 enhancer and the transcription factor cluster consisting of the EGR2 binding site at the distal Il13 E+6.5 enhancer are critical in sensing the signals triggered by antigenic stimulation. Those enhancers, which are responsive to antigenic stimulation and are constitutively active, cooperate to generate greater transcriptional outputs. Our study reveals a novel mechanism underlying how antigenic stimulation induces robust Il13 mRNA expression in mouse mast cells.

Crosstalk Between Signaling Pathways Involved in the Regulation of Airway Smooth Muscle Cell Hyperplasia

Increased ASM mass, primarily due to ASM hyperplasia, has been recognized as a hallmark of airway remodeling in asthma. Increased ASM mass is the major contributor to the airway narrowing, thus worsening the bronchoconstriction in response to stimuli. Inflammatory mediators and growth factors released during inflammation induce increased ASM mass surrounding airway wall via increased ASM proliferation, diminished ASM apoptosis and increased ASM migration. Several major pathways, such as MAPKs, PI3K/AKT, JAK2/STAT3 and Rho kinase, have been reported to regulate these cellular activities in ASM and were reported to be interrelated at certain points. This article aims to provide an overview of the signaling pathways/molecules involved in ASM hyperplasia as well as the mapping of the interplay/crosstalk between these major pathways in mediating ASM hyperplasia. A more comprehensive understanding of the complexity of cellular signaling in ASM cells will enable more specific and safer drug development in the control of asthma.

The airway epithelium in asthma

Asthma is a genetically and phenotypically complex disease that has a major impact on global health. Signs and symptoms of asthma are caused by the obstruction of airflow through the airways. The epithelium that lines the airways plays a major role in maintaining airway patency and in host defense. The epithelium initiates responses to inhaled or aspirated substances, including allergens, viruses, and bacteria, and epithelial-derived cytokines are important in the recruitment and activation of immune cells in the airway. Changes in the structure and function of the airway epithelium are a prominent feature of asthma. Approximately half of individuals with asthma have evidence of active type 2 immune responses in the airway. In these individuals, epithelial cytokines promote type 2 responses, and responses to type 2 cytokines result in increased epithelial mucus production and other effects that cause airway obstruction. Recent work also implicates other epithelial responses, including interleukin-17, interferon and ER stress responses, that may contribute to asthma pathogenesis and provide new targets for therapy.

Intranasal instillation of miR‑410 targeting IL‑4/IL‑13 attenuates airway inflammation in OVA‑induced asthmatic mice

Asthma is a common chronic inflammatory respiratory disease characterised by airway inflammation and hyperresponsiveness. The present study was designed to clarify the effect of intranasal miR-410 administration in an ovalbumin (OVA)-induced murine model of asthma. It was found that miR-410 expression was significantly decreased in the lungs of OVA-induced asthmatic mice (P<0.05) and miR-410 was overexpressed via intranasal instillation. Bioinformatics indicated that the 3′-untranslated regions of interleukin (IL)-4 and IL-13 messenger RNAs (mRNAs) contain miR-410 binding sites. The IL-4 and IL-13 genes were confirmed to be miR-410-regulated using the dual-luciferase reporter assay. Additionally, intranasal administration of miR-410 markedly attenuated airway inflammation and reduced infiltration of inflammatory cells into bronchoalveolar lavage fluid (P<0.05) as determined by bronchoalveolar lavage fluid analysis. Moreover, miR-410 significantly decreased the lung expression of IL-4 and IL-13 (P<0.05), although the levels of mRNAs encoding IL-4 and IL-13 in lungs did not change significantly as determined by real-time PCR analysis. In conclusion, we found that intranasal administration of miR-410 effectively inhibited airway inflammation in OVA-induced asthmatic mice by targeting IL-4 and IL-13 at the post-transcriptional level. miR-410 is thus a promising treatment for allergic asthma.

Mast cells in asthma--state of the art

Mast cells (MCs) play a central role in tissue homoeostasis, sensing the local environment through numerous innate cell surface receptors. This enables them to respond rapidly to perceived tissue insults with a view to initiating a co-ordinated programme of inflammation and repair. However, when the tissue insult is chronic, the ongoing release of multiple pro-inflammatory mediators, proteases, cytokines and chemokines leads to tissue damage and remodelling. In asthma, there is strong evidence of ongoing MC activation, and their mediators and cell-cell signals are capable of regulating many facets of asthma pathophysiology. This article reviews the evidence behind this.

Th2 Cytokines Augment IL-31/IL-31RA Interactions via STAT6-dependent IL-31RA Expression

Interleukin 31 receptor α (IL-31RA) is a novel Type I cytokine receptor that pairs with oncostatin M receptor to mediate IL-31 signaling. Binding of IL-31 to its receptor results in the phosphorylation and activation of STATs, MAPK, and JNK signaling pathways. IL-31 plays a pathogenic role in tissue inflammation, particularly in allergic diseases. Recent studies demonstrate IL-31RA expression and signaling in non-hematopoietic cells, but this receptor is poorly studied in immune cells. Macrophages are key immune-effector cells that play a critical role in Th2-cytokine-mediated allergic diseases. Here, we demonstrate that Th2 cytokines IL-4 and IL-13 are capable of up-regulating IL-31RA expression on both peritoneal and bone marrow-derived macrophages from mice. Our data also demonstrate that IL-4Rα-driven IL-31RA expression is STAT6 dependent in macrophages. Notably, the inflammation-associated genes Fizz1 and serum amyloid A (SAA) are significantly up-regulated in M2 macrophages stimulated with IL-31, but not in IL-4 receptor-deficient macrophages. Furthermore, the absence of Type II IL-4 receptor signaling is sufficient to attenuate the expression of IL-31RA in vivo during allergic asthma induced by soluble egg antigen, which may suggest a role for IL-31 signaling in Th2 cytokine-driven inflammation and allergic responses. Our study reveals an important counter-regulatory role between Th2 cytokine and IL-31 signaling involved in allergic diseases.

Human parainfluenza virus type 3 (HPIV3) induces production of IFNγ and RANTES in human nasal epithelial cells (HNECs)

Background

Human parainfluenza virus type 3 (HPIV3), while infecting lower airway epithelial cells induces pneumonia and bronchiolitis in infants and children, and may lead to asthma exacerbations in children and adults. Respiratory viruses invading the airway epithelium activate innate immune response and induce inflammatory cytokine release contributing to the pathophysiology of upper and lower airway disorders. However, the effects of HPIV3 infection on nasal epithelial cells have not been well defined.

The aim of this study was to evaluate the effect of the HPIV3 infection on cultured human nasal epithelial cells (HNECs) and the release of interferon gamma and other cytokines.

Methods

RPMI 2650, a human nasal epithelial cell line was cultured into confluence and was infected with HPIV3 (MOI of 0.1, 0.01 and 0.001). The protein release into supernatants and mRNA expression of selected cytokines were assessed 24, 48 and 72 h after infection. Cytokine concentrations in supernatants were measured by ELISA and expression of cytokine mRNA in RPMI 2650 cells confirmed by real time RT-PCR analysis.

Results

HNECs infection with HPIV3 did not induce cytotoxicity for at least 48 hours, but significantly increased IFN-γ protein concentration in the cell supernatants at 24 h and 48 h post infection (by 387% and 485% respectively as compared to mock infected cells). At 24 h a significant increase in expression of mRNA for IFNγ was observed. RANTES protein concentration and mRNA expression were significantly increased at 72 h after infection (mean protein concentration: 3.5 ± 1.4 pg/mL for 0.001 MOI, 10.8 ± 4.6 pg/mL for 0.01 MOI and 61.5 ± 18.4 pg/mL for 0.1 MOI as compared to 2.4 ± 1.3 pg/mL for uninfected cells). No measurable concentrations of TNF-α, IL-10, TSLP, IL-8, GM-CSF or eotaxin, were detected in virus infected cells supernatants.

Conclusions

HPIV3 effectively infects upper airway epithelial cells and the infection is associated with induction of IFN-γ and generation of RANTES.

Dissociation of FK506-binding protein 12.6 kD from ryanodine receptor in bronchial smooth muscle cells in airway hyperresponsiveness in asthma

Airway hyperresponsiveness (AHR) in asthma is predominantly caused by increased sensitivity of bronchial smooth muscle cells (BSMCs) to stimuli. The sarcoplasmic reticulum (SR)-Ca(2+) release channel, known as ryanodine receptor (RyR), mediates the contractive response of BSMCs to stimuli. FK506-binding protein 12.6 kD (FKBP12.6) stabilizes the RyR2 channel in a closed state. However, the interaction of FKBP12.6 with RyR2 in AHR remains unknown. This study examined the interaction of FKBP12.6 with RyR2 in BSMCs in AHR of asthma. The interaction of FKBP12.6 with RyR2 and FKBP12.6 expression was determined in a rat asthma model and in BSMCs treated with inflammatory cytokines. The calcium responses to contractile agonists were determined in BSMCs with overexpression and knockdown of FKBP12.6. Asthmatic serum, IL-5, IL-13, and TNF-α enhance the calcium response of BSMCs to contractile agonists and cause dissociation of FKBP12.6 from RyR2 and a decrease in FKBP12.6 gene expression in BSMCs in culture and in ovalbumin (OVA)-sensitized and -challenged rats. Knockdown of FKBP12.6 in BSMCs causes a decrease in the association of RyR2 with FKBP12.6 and an increase in the calcium response of BSMCs. Overexpression of FKBP12.6 increases the association of FKBP12.6 with RyR2, decreases the calcium response of BSMCs, and normalizes airway responsiveness in OVA-sensitized and -challenged rats. Dissociation of FKBP12.6 from RyR2 in BSMCs is responsible for the increased calcium response contributing to AHR in asthma. Manipulating the interaction of FKBP12.6 with RyR2 might be a novel and useful treatment for asthma.

A molecular perspective on TH2-promoting cytokine receptors in patients with allergic disease

The cytokines IL-4, IL-13, and thymic stromal lymphopoietin play a key role in allergic disease by virtue of their ability to initiate, maintain, and augment TH2 responses. These molecules mediate their effects through type 1 cytokine receptors, which bind cytokines with a characteristic structure. Receptors are expressed on a broad array of immune cell types and are integral to complex cytokine networks operating in health and disease. TH2-promoting cytokines bind different configurations of receptors. Receptor subunits can exist in surface-bound or soluble forms, as well as in isolation or in partnership with other subunits. Sharing of receptor subunits among different cytokine receptor complexes adds to the intricate landscape. This article describes the characteristics of receptors for IL-4, IL-13, and thymic stromal lymphopoietin and their respective ligands from a structure-function perspective. We detail the mechanisms of receptor complex assembly, the interrelated nature of these receptors, and the effect on allergic inflammation. The ability for novel and atypical types of receptors to modulate inflammatory processes is also discussed. We highlight current and emerging treatments that target TH2-promoting receptor complexes. Understanding the molecular features of these receptors provides insight into different disease phenotypes and the variable clinical outcomes arising from targeted therapies. These considerations can be used to inform future directions for research and creative strategies for treating individual patients.

Curine inhibits eosinophil activation and airway hyper-responsiveness in a mouse model of allergic asthma

Allergic asthma is a chronic inflammatory airway disease with increasing prevalence around the world. Current asthma therapy includes drugs that usually cause significant side effects, justifying the search for new anti-asthmatic drugs. Curine is a bisbenzylisoquinoline alkaloid that modulates calcium influx in many cell types; however, its anti-allergic and putative toxic effects remain to be elucidated. Our aim was to investigate the effects of curine on eosinophil activation and airway hyper-responsiveness (AHR) and to characterize its potential toxic effects. We used a mouse model of allergic asthma induced by sensitization and challenge with ovalbumin (OVA) to evaluate the anti-allergic effects of oral treatment with curine. The oral administration of curine significantly inhibited eosinophilic inflammation, eosinophil lipid body formation and AHR in animals challenged with OVA compared with animals in the untreated group. The curine treatment also reduced eotaxin and IL-13 production triggered by OVA. Verapamil, a calcium channel antagonist, had similar anti-allergic properties, and curine pre-treatment inhibited the calcium-induced tracheal contractile response ex-vivo, suggesting that the mechanism by which curine exerts its effects is through the inhibition of a calcium-dependent response. A toxicological evaluation showed that orally administered curine did not significantly alter the biochemical, hematological, behavioral and physical parameters measured in the experimental animals compared with saline-treated animals. In conclusion, curine showed anti-allergic activity through mechanisms that involve inhibition of IL-13 and eotaxin and of Ca(++) influx, without inducing evident toxicity and as such, has the potential for the development of anti-asthmatic drugs.

IL-13 R110Q, a Naturally Occurring IL-13 Polymorphism, Confers Enhanced Functional Activity in Cultured Human Bronchial Smooth Muscle Cells

Purpose

Interleukin (IL)-13, a Th2-type cytokine, plays a pivotal role in the pathogenesis of asthma through its direct effects on airway smooth muscles. A naturally occurring IL-13 polymorphism, R110Q, is strongly associated with increased total serum IgE levels and asthma. In the present study, we aimed to determine whether the IL-13 R110Q variant would display different biochemical properties or altered functions in comparison with wild-type (WT) IL-13 in cultured human bronchial smooth muscle cells (hBSMCs).

Methods

Culture supernatants and cell proteins were collected from cultured hBSMCs that were treated with 50 ng/mL IL-13 or IL-13 R110Q for 24 hours. Eotaxin released into hBSMC culture medium was determined by ELISA. The expression levels of the high-affinity IgE receptor (FcεRI) α-chain, smooth muscle-specific actin alpha chain (α-SMA), smooth muscle myosin heavy chain (SmMHC), and calreticulin in the cells were measured on Western blots.

Results

Compared with WT IL-13, treatment with the IL-13 R110Q variant resulted in a significant increase in eotaxin release as well as significant, although modest, increases in the expression levels of α-SMA, SmMHC, calreticulin, and FcεRI α-chain.

Conclusions

The results of the present study suggenst that the IL-13 R110Q variant may enhance enhanced functional activities in hBSMCs.

Neuronal chemorepellent Semaphorin 3E inhibits human airway smooth muscle cell proliferation and migration

BACKGROUND

Chronic airway diseases, including asthma, are characterized by increased airway smooth muscle (ASM) mass that is due in part to growth factor-mediated ASM cell proliferation and migration. However, the molecular mechanisms underlying these effects are not completely understood. Semaphorin 3E (Sema3E) has emerged as an essential mediator involved in cell migration, proliferation, and angiogenesis, although its role in ASM cell function is not investigated.

OBJECTIVES

We sought to determine the expression of Sema3E receptor, plexinD1, in human ASM cells (HASMCs); effect of Sema3E on basal and platelet-derived growth factor (PDGF)-induced proliferation and migration; and underlying signaling pathways.

METHODS

Expression of plexinD1 in HASMCs was studied with RT-PCR, immunostaining, and flow cytometry. The effect of Sema3E on HASMC proliferation and migration was evaluated by 5-ethynyl-2'-deoxyuridine (EdU) incorporation, cell count, and Boyden chamber assay. Sema3E-mediated intracellular signaling was investigated with fluorescent microscopy, flow cytometry, Rac1 activation, and Western blot analysis.

RESULTS

HASMCs from healthy persons expressed plexinD1 more than HASMCs from asthmatic patients. Sema3E increased plexinD1 expression in HASMCs from asthmatic patients. Recombinant Sema3E inhibited PDGF-mediated HASMC proliferation and migration, which was associated with F-actin depolymerization, suppression of PDGF-induced Rac1 guanosine triphosphatase activity, and Akt and extracellular signal-regulated kinase 1 and 2 phosphorylation. Bronchial biopsies from patients with mild asthma displayed immunoreactivity of plexinD1, suggesting the potential in vivo role of Sema3E-PlexinD1 axis in HASMC function.

CONCLUSION

This study provides the first evidence that Sema3E receptor is expressed and plays functional roles in HASMCs. Our data suggest a regulatory role of Sema3E in PDGF-mediated proliferation and migration, leading to downregulation of ASM remodeling.

Chronic rhinosinusitis with polyps and without polyps is associated with increased expression of suppressors of cytokine signaling 1 and 3

BACKGROUND

Chronic rhinosinusitis with nasal polyps (CRSwNP) or without nasal polyps (CRSsNP) is associated with expression of various cytokines. Suppressors of cytokine signaling (SOCS) regulate cytokine activity in a variety of cells, modulating inflammatory responses.

OBJECTIVE

We analyzed the expression and distribution pattern of SOCS1 and SOCS3 in CRSwNP and CRSsNP, and their cytokine-driven expression regulation in sinus mucosa. In addition, the expression levels of various cytokines were evaluated in CRSwNP and CRSsNP.

METHODS

The expression levels of SOCS1 and SOCS3 in CRSwNP and CRSsNP and in control samples were assessed by using real-time PCR, Western blot, and immunohistochemistry. Nasal epithelial cell culture was used to elucidate the effect of IL-4, IL-5, IL-6, IL-10, IL-13, IFN-γ, TNF-α, and TGF-β1 on SOCS1 and SOCS3 expression in sinus mucosa. The expression levels of these cytokines were also evaluated in normal and inflammatory sinus mucosa by using real-time PCR and Western blot.

RESULTS

The expression levels of SOCS1 and SOCS3 were increased in CRS, irrespective of the presence of nasal polyp, and they were distributed in superficial epithelium, submucosal glands, and vascular endothelium in sinus mucosa. SOCS1 was induced by IL-4, IL-13, IFN-γ, and TNF-α, while SOCS3 expression was upregulated by IL-6, IL-13, IFN-γ, and TNF-α. IL-4 and IL-13 levels were increased in CRSwNP, while IL-4, IFN-γ, TNF-α, and TGF-β1 levels were increased in CRSsNP.

CONCLUSION

SOCS1 and SOCS3 are increased in CRS, irrespective of nasal polyp presence. This may be a response to elevated levels of various cytokines increasingly expressed in inflammatory sinus mucosa.

Airway smooth muscle in the pathophysiology and treatment of asthma

Airway smooth muscle (ASM) plays an integral part in the pathophysiology of asthma. It is responsible for acute bronchoconstriction, which is potentiated by constrictor hyperresponsiveness, impaired relaxation and length adaptation. ASM also contributes to airway remodeling and inflammation in asthma. In light of this, ASM is an important target in the treatment of asthma.

Interleukin-13-induced activation of signal transducer and activator of transcription 6 is mediated by an activation of Janus kinase 1 in cultured human bronchial smooth muscle cells

BACKGROUND

The current study was carried out to identify the JAK molecule(s) that is involved in the IL-13-induced activation of STAT6 in cultured human bronchial smooth muscle cells (hBSMCs).

METHODS

Cultured hBSMCs were stimulated with IL-13 in the absence and presence of JAK inhibitor-I (a nonspecific JAKs inhibitor), tyrphostin-AG490 (a specific JAK2 inhibitor), WHI-P131 (a specific JAK3 inhibitor), or tyrphostin-AG9 (a specific Tyk2 inhibitor), and levels of phosphorylated STAT6 were measured by immunoblot analyses.

RESULTS

The IL-13-induced phosphorylation of STAT6 was abolished by JAK inhibitor-I, whereas the other inhibitors had no significant effect.

CONCLUSION

These findings indicate that the STAT6 phosphorylation/activation induced by IL-13 is mediated by an activation of JAK1 in cultured hBSMCs.

MAPK regulation of IL-4/IL-13 receptors contributes to the synergistic increase in CCL11/eotaxin-1 in response to TGF-β1 and IL-13 in human airway fibroblasts

CCL11/eotaxin-1 is a potent eosinophilic CC chemokine expressed by primary human fibroblasts. The combination of TGF-β1 and IL-13 synergistically increases CCL11 expression, but the mechanisms behind the synergy are unclear. To address this, human airway fibroblast cultures from normal and asthmatic subjects were exposed to IL-13 alone or TGF-β1 plus IL-13. Transcriptional (nuclear run-on) and posttranscriptional (mRNA stability) assays confirmed that transcriptional regulation is critical for synergistic expression of CCL11. TGF-β1 plus IL-13 synergistically increased STAT-6 phosphorylation, nuclear translocation, and binding to the CCL11 promoter as compared with IL-13 alone. STAT-6 small interfering RNA significantly knocked down both STAT-6 mRNA expression and phosphorylation and inhibited CCL11 mRNA and protein expression. Regulation of the IL-4Rα complex by TGF-β1 augmented IL-13 signaling by dampening IL-13Rα2 expression, overcoming IL-13's autoregulation of its pathway and enhancing the expression of CCL11. Our data suggest that TGF-β1 induced activation of the MEK/ERK pathway reduces IL-13Rα2 expression induced by IL-13. Thus, TGF-β1, a pleiotropic cytokine upregulated in asthmatic airways, can augment eosinophilic inflammation by interfering with IL-13's negative feedback autoregulatory loop under MEK/ERK-dependent conditions.

IL-13 antibodies influence IL-13 clearance in humans by modulating scavenger activity of IL-13Rα2

Human studies using Abs to two different, nonoverlapping epitopes of IL-13 suggested that epitope specificity can have a clinically significant impact on clearance of IL-13. We propose that Ab modulation of IL-13 interaction with IL-13Rα2 underlies this effect. Two Abs were administered to healthy subjects and mild asthmatics in separate dose-ranging studies and allergen-challenge studies. IMA-638 allows IL-13 interaction with IL-13Rα1 or IL-13Rα2 but blocks recruitment of IL-4Rα to the IL-13/IL-13Rα1 complex, whereas IMA-026 competes with IL-13 interaction with IL-13Rα1 and IL-13Rα2. We found ∼10-fold higher circulating titer of captured IL-13 in subjects treated with IMA-026 compared with those administered IMA-638. To understand how this difference could be related to epitope, we asked whether either Ab affects IL-13 internalization through cell surface IL-13Rα2. Humans inducibly express cell surface IL-13Rα2 but lack the soluble form that regulates IL-13 responses in mice. Cells with high IL-13Rα2 expression rapidly and efficiently depleted extracellular IL-13, and this activity persisted in the presence of IMA-638 but not IMA-026. The potency and efficiency of this clearance pathway suggest that cell surface IL-13Rα2 acts as a scavenger for IL-13. These findings could have important implications for the design and characterization of IL-13 antagonists.

Blackcurrant proanthocyanidins augment IFN-gamma-induced suppression of IL-4 stimulated CCL26 secretion in alveolar epithelial cells

Epidemiological studies reveal that fruit consumption reduces the prevalence of airway inflammation and childhood asthma. In particular, blackcurrant polyphenolic extracts have been shown to alleviate lung inflammation. Since IL-4-stimulated eotaxin-3 (CCL26) secretion is a major factor in the continuous eosinophil recruitment observed in atopic asthma, our focus was to evaluate the effectiveness of blackcurrant polyphenolic compounds on CCL26 secretion in human alveolar epithelial cells. Our results indicate that a proanthocyanin-enriched blackcurrant extract (BC-P), but not anthocyanin-enriched blackcurrant extract suppressed both IL-4- and IL-13-stimulated CCL26 secretion in a dose-dependent manner. Furthermore pre-incubation of cells with BC-P caused a time-dependent suppression of IL-4-stimulated CCL26 secretion. Moreover, epigallocatechin (EGC), and to a lesser extent epicatechin, metabolites identified in the proanthocyanidin extract, suppressed IL-4-stimulated CCL26 secretion. EGC was also effective at reducing the cellular phosphorylated STAT-6/STAT-6 ratio. Furthermore, both BC-P and purified EGC potentiated the ability of IFN-gamma to suppress IL-4-stimulated CCL26 secretion. The progression of an allergic immune response is complex, identifying plant compounds that target specific cellular events and complement the body's own immune actions is important for the development of functional foods. Our findings support the potential for blackcurrant polyphenolic compounds to reduce eosinophil recruitment and alleviate eosinophilic-driven airway inflammation.

Asthma susceptible genes in Chinese population: a meta-analysis

BACKGROUND

Published data regarding the associations between genetic variants and asthma risk in Chinese population were inconclusive. The aim of this study was to investigate asthma susceptible genes in Chinese population.

METHODS

The authors conducted 18 meta-analyzes for 18 polymorphisms in 13 genes from eighty-two publications.

RESULTS

Seven polymorphisms were found being associated with risk of asthma, namely: A Disintegrin and Metalloprotease 33 (ADAM33) T1-C/T (odds ratio [OR] = 6.07, 95% confidence interval [CI]: 2.69-13.73), Angiotensin-Converting Enzyme (ACE) D/I (OR = 3.85, 95%CI: 2.49-5.94), High-affinity IgE receptor β chain (FcεRIβ) -6843G/A (OR = 1.49, 95%CI: 1.01-2.22), Interleukin 13(IL-13) -1923C/T (OR = 2.99, 95%CI: 2.12-4.24), IL-13 -2044A/G (OR = 1.49, 95%CI: 1.07-2.08), Regulated upon Activation, Normal T cell Expressed and Secreted (RANTES) -28C/G (OR = 1.64, 95%CI: 1.09-2.46), Tumor Necrosis Factor-α (TNF-α) -308G/A(OR = 1.42, 95%CI: 1.09, 1.85). After subgroup analysis by age, the ACE D/I, β2-Adrenergic Receptor (β2-AR) -79G/C, TNF-α -308G/A, Interleukin 4 receptor(IL-4R) -1902G/A and IL-13 -1923C/T polymorphisms were found significantly associated with asthma risk in Chinese children. In addition, the ACE D/I, FcεRIβ -6843G/A, TNF-α -308G/A, IL-13 -1923C/T and IL-13 -2044A/G polymorphisms were associated with asthma risk in Chinese adults.

CONCLUSION

ADAM33, FcεRIβ, RANTES, TNF-α, ACE, β2-AR, IL-4R and IL-13 genes could be proposed as asthma susceptible genes in Chinese population. Given the limited number of studies, more data are required to validate these associations.

Aqueous extracts from dietary supplements influence the production of inflammatory cytokines in immortalized and primary T lymphocytes

BACKGROUND

Congaplex and Immuplex are dietary supplements that have been traditionally used to support immune system function. The purpose of these experiments was to determine whether Congaplex and Immuplex affect immune function using primary and immortalized T lymphocytes.

METHODS

Immortalized CEM and Jurkat T lymphocytes and primary peripheral mononuclear blood cells (PBMCs) were treated with the aqueous extracts from Congaplex and Immuplex to determine the effects of these products on cytokine production in activated T lymphocytes.

RESULTS

Congaplex enhanced phytohemagglutinin/phorbol 12-myristate 13-acetate (PHA/PMA) stimulation of both CEM and Jurkat cells as measured by the production of cytokines, while Immuplex suppressed PHA/PMA-induced production of cytokines, with the exception of interleukin (IL)-8 which was enhanced by Immuplex. In vitro treatment of PBMCs from 10 healthy donors with Congaplex or Immuplex decreased PHA-stimulated production of interferon (IFN)-gamma but increased the production of IL-13.

CONCLUSIONS

While the effects of Congaplex and Immuplex differed in these two models, these data demonstrate that the aqueous extracts from these two dietary supplements can affect the inflammatory response of T lymphocytes.