Interleukin-4, interleukin-13, signal transducer and activator of transcription factor 6, and allergic asthma

Degradation of IL-4Ralpha by Immunoproteasome: implication in airway type 2 inflammation and hyperresponsiveness

Introduction

Immunoproteasome (IP) is induced by pro-inflammatory stimuli such as interferon gamma to regulate inflammation and immunity. Asthma patients with airway type 2 high inflammation (e.g., IL-13) demonstrate more eosinophils and airway hyperresponsiveness (AHR) with less interferon gamma. The role of IP in regulating airway eosinophilic inflammation and AHR has not been investigated.

Methods

This study was aimed to determine how IP regulates type 2 inflammation and AHR using LMP7 (a subunit of IP) deficient mouse lungs, precision-cut lung slices (PCLS), and cultured human airway epithelial cells treated with IL-13 in the absence or presence of an IP inhibitor ONX-0914 or exogenous IP.

Results

LMP7 KO mouse lungs had significantly more IL-4Rα protein expression than the wildtype (WT) mice. Following IL-13 treatment in PCLS, LMP7 KO mice had significantly more airway contraction than WT mice, which was coupled with increased eotaxin-2 levels. IP inhibition by ONX-0914 in IL-13 treated human airway epithelial cells resulted in significantly more IL-4Rα protein expression and eotaxin-3 release. IP inhibition in human PCLS significantly increased AHR.

Conclusion

Collectively, these data demonstrated that IP promotes degradation of IL-4Rα, while inhibits type 2 inflammation and AHR. Enhancement of IP expression or activity may serve as an alternative approach to reduce the severity of type 2 inflammation and AHR.

Inhibition of FABP4 Ameliorates IL-13-Induced Inflammatory Response and Barrier Dysfunction in Nasal Mucosal Epithelial Cells through the Regulation of Ferroptosis

This study was conducted to investigate the role and the mechanism of fatty acid-binding protein 4 (FABP4) in allergic rhinitis (AR). To induce AR in vitro, human nasal epithelial cells (hNECs) were treated by interleukin (IL)-13. Real-time reverse transcriptase-polymerase chain reaction (RT-qPCR) and western blot were used to detect FABP4 expression. Enzyme-linked immunosorbent assay (ELISA) was used to detect the inflammatory level while inflammation-related proteins were detected by western blot. Immunofluorescence (IF) assay was used to detect mucin-5AC (MUC5AC) and zonula occludens-1 (ZO-1) level. The expressions of tight junction proteins were detected by western blot. Lipid reactive oxygen species (ROS) was detected using a BODIPY 581/591 C11 kit and iron level was detected by corresponding assay kits. Ferroptosis-related proteins were detected by western blot. With the goal of investigating the mechanism of FABP4 associated with ferroptosis, cells were pretreated by ferroptosis inducer erastin (30 mM) and rescue experiments were implemented. In this work, FABP4 expression was increased in hNECs treated by IL-13. After FABP4 was knocked down, the inflammation, mucus production, barrier dysfunction and ferroptosis induced by IL-13 in hNECs were all repressed. Nevertheless, erastin pre-treatment partially counteracted the protective role of FABP4 depletion against inflammation, mucus production and barrier dysfunction in IL-13-treated hNECs. In summary, FABP4 deficiency ameliorated IL-13-induced inflammatory response and barrier dysfunction in nasal mucosal epithelial cells through the regulation of ferroptosis.

Inhibition of IL-4/STAT6/IRF4 signaling reduces the epithelial-mesenchymal transition in eosinophilic chronic rhinosinusitis with nasal polyps

BACKGROUND

Previous studies have shown that epithelial-to-mesenchymal transition (EMT) in nasal epithelial cells is critical for tissue remodeling of chronic rhinosinusitis with nasal polyps (CRSwNP). However, the precise mechanism underlying the EMT remains poorly understood. This study aimed to investigate the role of interleukin-4 (IL-4)/signal transducer and activator of transcription 6 (STAT6)/interferon regulatory factor 4 (IRF4) signaling pathway on EMT in eosinophilic CRSwNP.

METHODS

We performed quantitative real-time polymerase chain reaction, immunohistochemistry, immunofluorescent staining, and Western blotting to evaluate the expression of STAT6, IRF4, and EMT markers in sinonasal mucosal samples. Effects of IL-4-induced EMT were determined using primary human nasal epithelial cells (hNECs) from patients with eosinophilic CRSwNP. Wound scratch assay, cell morphology, Western blotting, and immunofluorescence cytochemistry were performed to evaluate EMT, and EMT-related markers. Next, human THP-1 monocytic cells were stimulated by phorbolate-12-myristate-13-acetate to differentiate into M0 and were subsequently polarized into M1 with lipopolysaccharide and interferon-γ, M2 with IL-4. The markers of the macrophage phenotype were assessed by Western blotting. The co-culture system was built to explore the interaction between macrophages (THP-1 cells) and hNECs. After co-culture with M2 macrophages, EMT-related markers of primary hNECs were evaluated by immunofluorescence cytochemistry and Western blotting. Enzymelinked immunosorbent assays were used to detect transforming growth factor beta 1 (TGF-β1) in THP-1-derived supernatants.

RESULTS

STAT6 and IRF4 mRNA and protein expression were significantly upregulated in both eosinophilic and noneosinophilic nasal polyps compared with control tissues. The expression of STAT6 and IRF4 in eosinophilic nasal polyps was higher than those in noneosinophilic nasal polyps. STAT6 and IRF4 were not only expressed in epithelial cells but also in macrophages. The number of STAT6⁺CD68⁺ cells and IRF4⁺CD68⁺ cells in eosinophilic nasal polyps was higher than those in noneosinophilic nasal polyps and control tissues. EMT was enhanced in eosinophilic CRSwNP compared to the healthy controls and noneosinophilic CRSwNP. IL-4-stimulated human nasal epithelial cells exhibited EMT characteristics. The hNECs co-cultured with M2 macrophages demonstrated high levels of EMT-related markers. The TGF-β1 level was significantly induced by IL-4 and elevated (M2) rather than control macrophages. The inhibition of STAT6 by AS1517499 reduced the expression of IRF4 in epithelial cells and macrophages and counteracted IL-4-induced EMT in epithelial cells.

CONCLUSION

In eosinophilic nasal polyps, IL-4 induces STAT6 signaling to upregulate IRF4 expression in epithelial cells and macrophages. IL-4 promotes EMT of hNECs through the STAT6/IRF4 signaling pathway. IL-4-induced M2 macrophages enhanced EMT of hNECs. Inhibition of STAT6 can downregulate the expression of IRF4 and suppress the EMT process, thus providing a new strategy for the treatment of nasal polyps.

Gleditsia sinensis Lam. aqueous extract attenuates nasal inflammation in allergic rhinitis by inhibiting MUC5AC production through suppression of the STAT3/STAT6 pathway

Allergic rhinitis (AR), a chronic respiratory inflammatory disease, is among the most common chronic diseases reported worldwide. Mucus hypersecretion is a critical feature of AR pathogenesis. Although the Gleditsia sinensis extract has several beneficial effects on human health, its effects on allergic inflammation have not yet been investigated. In this study, we examined the effects of G. sinensis aqueous extract (GSAE) on nasal inflammation in an ovalbumin (OVA)-induced AR mouse model. GSAE was administered orally for 1 week and then the clinical nasal symptoms were evaluated. The levels of histamine, OVA-specific immunoglobulin (Ig) E, and interleukin (IL)-13 were measured in the serum using an enzyme-linked immunosorbent assay (ELISA). Inflammatory cells were then counted in the nasal lavage fluid (NALF) and histopathology in the nasal epithelium was evaluated. STAT3/STAT6 phosphorylation was examined in primary human nasal epithelial cells (HNEpCs) using western blot analysis. Oral administration of GSAE to OVA-induced AR mice alleviated nasal clinical symptoms and reduced OVA-specific immunoglobulin E, interleukin (IL)-13, and histamine levels. The accumulation of eosinophils in nasal lavage fluid, nasal mucosa, mast cells, goblet cells, and mucin 5AC (MUC5AC) in the nasal epithelium was also inhibited by GSAE. Treatment with GSAE inhibited the production of MUC5AC in IL-4/IL-13-stimulated primary human nasal epithelial cells through the signal transducer and activator of transcription (STAT)3/STAT6 signaling pathway. These results indicated that GSAE reduces nasal inflammation suggesting that it is a potential treatment option for AR.

Anti-inflammatory effects of medications used for viral infection-induced respiratory diseases

Respiratory viruses like rhinovirus, influenza virus, respiratory syncytial virus, and coronavirus cause several respiratory diseases, such as bronchitis, pneumonia, pulmonary fibrosis, and coronavirus disease 2019, and exacerbate bronchial asthma, chronic obstructive pulmonary disease, bronchiectasis, and diffuse panbronchiolitis. The production of inflammatory mediators and mucin and the accumulation of inflammatory cells have been reported in patients with viral infection-induced respiratory diseases. Interleukin (IL)-1β, IL-6, IL-8, tumor necrosis factor-α, granulocyte-macrophage colony-stimulating factor, and regulated on activation normal T-cell expressed and secreted are produced in the cells, including human airway and alveolar epithelial cells, partly through the activation of toll-like receptors, nuclear factor kappa B and p44/42 mitogen-activated protein kinase. These mediators are associated with the development of viral infection-induced respiratory diseases through the induction of inflammation and injury in the airway and lung, airway remodeling and hyperresponsiveness, and mucus secretion. Medications used to treat respiratory diseases, including corticosteroids, long-acting β2-agonists, long-acting muscarinic antagonists, mucolytic agents, antiviral drugs for severe acute respiratory syndrome coronavirus 2 and influenza virus, macrolides, and Kampo medicines, reduce the production of viral infection-induced mediators, including cytokines and mucin, as determined in clinical, in vivo, or in vitro studies. These results suggest that the anti-inflammatory effects of these medications on viral infection-induced respiratory diseases may be associated with clinical benefits, such as improvements in symptoms, quality of life, and mortality rate, and can prevent hospitalization and the exacerbation of chronic obstructive pulmonary disease, bronchial asthma, bronchiectasis, and diffuse panbronchiolitis.

Identification of the α2 chain of interleukin-13 receptor as a potential biomarker for predicting castration resistance of prostate cancer using patient-derived xenograft models

BACKGROUND

Several treatment strategies use upfront chemotherapy or androgen receptor axis-targeting therapies for metastatic prostate cancer. However, there are no useful biomarkers for selecting appropriate patients who urgently require these treatments.

METHODS

Novel patient-derived xenograft (PDX) castration-sensitive and -resistant models were established and gene expression patterns were comprehensively compared. The function of a gene highly expressed in the castration-resistant models was evaluated by its overexpression in LNCaP prostate cancer cells. Protein expression in the tumors and serum of patients was examined by immunohistochemistry and ELISA, and correlations with castration resistance were analyzed.

RESULTS

Expression of the α2 chain of interleukin-13 receptor (IL13Rα2) was higher in castration-resistant PDX tumors. LNCaP cells overexpressing IL13Rα2 acquired castration resistance in vitro and in vivo. In tissue samples, IL13Rα2 expression levels were significantly associated with castration-resistant progression (p < 0.05). In serum samples, IL13Rα2 levels could be measured in 5 of 28 (18%) castration-resistant prostate cancer patients.

CONCLUSION

IL13Rα2 was highly expressed in castration-resistant prostate cancer PDX models and was associated with the castration resistance of prostate cancer cells. It might be a potential tissue and serum biomarker for predicting castration resistance in prostate cancer patients.

STAT6-IP-Dependent Disruption of IL-33-Mediated ILC2 Expansion and Type 2 Innate Immunity in the Murine Lung

Recent interest has focused on innate-type cytokines as promoters of type 2 immunity and targets for drug development in asthma. IL-33 induces production of IL-4 and/or IL-13, which is associated with STAT6-dependent responses in innate cells, including group 2 innate lymphoid cells (ILC2s), macrophages, and eosinophils. Our published data show that STAT6-immunomodulatory peptide (STAT6-IP), an immunomodulatory peptide designed to inhibit the STAT6 transcription factor, reduces induction of Th2 adaptive immunity in respiratory syncytial virus infection and asthma models. Nevertheless, the mechanism of STAT6-IP-dependent inhibition has remained obscure. In this study, we demonstrate that STAT6-IP reduced IL-33-induced type 2 innate lung inflammation. Specifically, our data show that STAT6-IP reduced recruitment and activation of eosinophils as well as polarization of alternatively activated macrophages. Decreases in these cells correlated with reduced levels of IL-5 and IL-13 as well as several type 2 chemokines in the bronchoalveolar lavage fluid. STAT6-IP effectively inhibited expansion of ILC2s as well as the number of IL-5- and IL-13-producing ILC2s. Our data suggest that STAT6-IP effectively disrupts IL-13-dependent positive feedback loops, initiated by ILC2 activation, to suppress IL-33-induced type 2 innate immunity in the murine lung.

Autism: genetics, environmental stressors, maternal immune activation, and the male bias in autism

Autism spectrum disorder (ASD) is a class of neurodevelopmental disorders (NDD) characterized by deficits in three domains: impairments in social interactions, language, and communication, and increased stereotyped restrictive/repetitive behaviors and interests. The exact etiology of ASD remains unknown. Genetics, gestational exposure to inflammation, and environmental stressors, which combine to affect mitochondrial dysfunction and metabolism, are implicated yet poorly understood contributors and incompletely delineated pathways toward the relative risk of ASD. Many studies have shown a clear male bias in the incidence of ASD and other NDD. In other words, being male is a significant yet poorly understood risk factor for the development of NDD. This review discusses the link between these factors by looking at the current body of evidence. Understanding the link between the multiplicity of hits—from genes to environmental stressors and possible sexual determinants, contributing to autism susceptibility is critical to developing targeted interventions to mitigate these risks.

Investigational approaches for unmet need in severe asthma

INTRODUCTION

Molecular antibodies (mAb) targeting inflammatory mediators are effective in T2-high asthma. The recent approval of Tezepelumab presents a novel mAb therapeutic option for those with T2-low asthma.

AREAS COVERED

We discuss a number of clinical problems pertinent to severe asthma that are less responsive to current therapies, such as persistent airflow obstruction and airway hyperresponsiveness. We discuss selected investigational approaches, including a number of candidate therapies under investigation in two adaptive platform trials currently in progress, with particular reference to this unmet need, as well as their potential in phenotypes such as neutrophilic asthma and obese asthma, which may or may not overlap with a T2-high phenotype.

EXPERT OPINION

The application of discrete targeting approaches to T2-low molecular phenotypes, including those phenotypes in which inflammation may not arise within the airway, has yielded variable results to date. Endotypes associated with T2-low asthma are likely to be diverse but await validation. Investigational therapeutic approaches must, likewise, be diverse if the goal of remission is to become attainable for all those living with asthma.

The Precision Interventions for Severe and/or Exacerbation-Prone (PrecISE) Asthma Network: An overview of Network organization, procedures, and interventions

Asthma is a heterogeneous disease, with multiple underlying inflammatory pathways and structural airway abnormalities that impact disease persistence and severity. Recent progress has been made in developing targeted asthma therapeutics, especially for subjects with eosinophilic asthma. However, there is an unmet need for new approaches to treat patients with severe and exacerbation-prone asthma, who contribute disproportionately to disease burden. Extensive deep phenotyping has revealed the heterogeneous nature of severe asthma and identified distinct disease subtypes. A current challenge in the field is to translate new and emerging knowledge about different pathobiologic mechanisms in asthma into patient-specific therapies, with the ultimate goal of modifying the natural history of disease. Here, we describe the Precision Interventions for Severe and/or Exacerbation-Prone Asthma (PrecISE) Network, a groundbreaking collaborative effort of asthma researchers and biostatisticians from around the United States. The PrecISE Network was designed to conduct phase II/proof-of-concept clinical trials of precision interventions in the population with severe asthma, and is supported by the National Heart, Lung, and Blood Institute of the National Institutes of Health. Using an innovative adaptive platform trial design, the PrecISE Network will evaluate up to 6 interventions simultaneously in biomarker-defined subgroups of subjects. We review the development and organizational structure of the PrecISE Network, and choice of interventions being studied. We hope that the PrecISE Network will enhance our understanding of asthma subtypes and accelerate the development of therapeutics for severe asthma.

Sulforaphane inhibits cytokine-stimulated chemokine and adhesion molecule expressions in human corneal fibroblasts: Involvement of the MAPK, STAT, and NF-κB signaling pathways

Chemokines and adhesion molecules are major inflammatory mediators of chronic and recurrent vernal keratoconjunctivitis (VKC). Sulforaphane (SFN) is a natural plant extract that is known to have anti-inflammatory and antioxidant properties. SFN is demonstrated to be effective against a variety of human diseases. The current investigation examines the effects and the molecular mechanisms of SFN on cytokine-induced human corneal fibroblasts (HCFs) expression of adhesion molecules and chemokines. HCFs were exposed to both interleukin (IL)-4 and tumor necrosis factor (TNF)-α in the absence or presence of SFN treatment. The levels of thymus- and activation-regulated chemokine (TARC) and eotaxin-1 in culture supernatants were evaluated using enzyme-linked immunosorbent assay (ELISA). Reverse transcription-polymerase chain reaction analysis (RT-PCR) enabled quantification of mRNA levels of vascular cell adhesion molecule (VCAM)-1, eotaxin-1, and TARC along with cytokine receptors. An immunoblotting assay was used to evaluate the activities of VCAM-1, nuclear factor-kappa B (NF-κB), mitogen-activated protein kinases (MAPKs), signal transducer and activator of transcription factor (STAT)6 pathways, along with the expression of the cytokine receptors including IL-4 receptor (R)α, IL-13Rα1, TNFRI, as well as TNFRII. SFN inhibited TARC and eotaxin-1 release in HCFs stimulated by TNF-α and IL-4 in a manner dependent on dose and time. SFN suppressed transcriptions of TARC, eotaxin-1, and VCAM-1. Furthermore, the mRNA and protein expression levels of IL-4Rα, TNFRI, and TNFRII were also attenuated by SFN exposure, however, those of IL-13Rα1 remained unaffected. In addition, SFN downregulated the expression of VCAM-1 and the phosphorylation of MAPKs, IκBα, and STAT6. These results suggest that SFN inhibited cytokine-stimulated TARC, eotaxin-1 secretion as well as VCAM-1 expression in HCFs, with these effects likely occurring as a result of cytokine receptor inhibition and attenuation of MAPK, NF-κB, and STAT6 signaling. SFN may therefore have therapeutic potential in VKC treatment.

TSLP up-regulates inflammatory responses through induction of autophagy in T cells

Thymic stromal lymphopoietin (TSLP), a type I cytokine belonging to the IL-2 cytokine family, promotes Th2-mediated inflammatory responses. The aim of this study is to investigate whether TSLP increases inflammatory responses via induction of autophagy using a murine T cell lymphoma cell line, EL4 cells, and lipopolysaccharide (LPS)-injected mice. TSLP increased expression levels of autophagy-related factors, such as Beclin-1, LC3-II, p62, Atg5, and lysosome associated membrane protein 1/2, whereas these factors increased by TSLP disappeared by neutralization of TSLP in EL4 cells. TSLP activated JAK1/JAK2/STAT5/JNK/PI3K, while the blockade of JAK1/JAK2/STAT5/JNK/PI3K signaling pathways reduced the expression levels of Beclin-1, LC3-II, and p62 in TSLP-stimulated EL4 cells. In addition, TSLP simultaneously increased levels of inflammatory cytokines via induction of autophagy by activation of JAK1/JAK2/STAT5/JNK/PI3K signaling pathways. In an LPS-induced acute liver injury (ALI) mouse model, exogenous TSLP increased expression levels of Beclin-1 and LC3-II, whereas functional deficiency of TSLP by TSLP siRNA resulted in lower expression of Beclin-1, LC3-II, and inflammatory cytokines, impairing their ability to form autophagosomes in ALI mice. Thus, our findings show a new role of TSLP between autophagy and inflammatory responses. In conclusion, regulating TSLP-induced autophagy may be a potential therapeutic strategy for inflammatory responses.

Activation of STAT6 by intranasal allergens correlated with the development of eosinophilic chronic rhinosinusitis in a mouse model

Eosinophilic chronic rhinosinusitis (ECRS) is a chronic inflammatory disease characterized by prominent eosinophilic infiltration along with a T-helper-2 (Th2) response. It has been well documented that signal transducer and activator of transcription 6 (STAT6) is a nuclear transcription factor that mediates Th2-type immunity and is implicatory of STAT1 and STAT3 in the pathogenesis of allergic airway diseases. However, little is known about the association between STATs and ECRS. Here, we explored the relationship between STAT1, STAT3, and/or STAT6 and eosinophilic inflammation accompanied by Th2-type immunity in a mouse model of ECRS. An ovalbumin (OVA)-staphylococcal enterotoxin B (SEB)-induced ECRS murine model was first established. The mucosal histological alterations were determined using hematoxylin and eosin staining. The number of eosinophils in peripheral blood was measured using a blood cell analyzer. The cytokine (IL-4, IL-5, IL17 A and IFN-γ) expression levels in the sinonasal mucosa and total and OVA-specific IgE from serum were measured using ELISA. Then, the protein levels of STAT1, STAT3, STAT6, phosphorylated STAT1 (p-STAT1), p-STAT3, p-STAT6, T-box expressed in T-cells (T-bet), GATA binding protein 3 (GATA-3), and retinoic acid receptor-related orphan receptor γ (RORγt) in the sinonasal mucosa were examined by immunohistochemical staining or Western blotting. Local administration of OVA combined with SEB (OVA + SEB) induced multiple polyp-like lesions, accompanied by prominent eosinophilic infiltration in the sinonasal mucosa. The OVA- and OVA+SEB-treated groups showed significantly higher eosinophil counts from peripheral blood and total and OVA-specific IgE levels from serum than those in the PBS- and SEB-treated groups. The levels of p-STAT6 were markedly increased by OVA + SEB exposure, as well as GATA-3, IL-4, and IL-5, but did not affect STAT6, p-STAT1, p-STAT3, T-bet, RORγt, IFN-γ, or IL-17A. Furthermore, an eosinophil count in the sinonasal mucosa showed a positive correlation with the level of p-STAT6 in the ECRS mouse model. Signal transducer and activator of transcription 6 signaling could be activated in the OVA+SEB-induced ECRS model and might be a crucial signal transducer in the development of Th2-skewed ECRS.

IL-13 Controls IL-33 Activity through Modulation of ST2

IL-33 is a multifunctional cytokine that mediates local inflammation upon tissue damage. IL-33 is known to act on multiple cell types including group 2 innate lymphoid cells (ILC2s), Th2 cells, and mast cells to drive production of Th2 cytokines including IL-5 and IL-13. IL-33 signaling activity through transmembrane ST2L can be inhibited by soluble ST2 (sST2), which acts as a decoy receptor. Previous findings suggested that modulation of IL-13 levels in mice lacking decoy IL-13Rα2, or mice lacking IL-13, impacted responsiveness to IL-33. In this study, we used Il13 ^-/- mice to investigate whether IL-13 regulates IL-33 activity by modulating the transmembrane and soluble forms of ST2. In Il13 ^-/- mice, the effects of IL-33 administration were exacerbated relative to wild type (WT). Il13 ^-/- mice administered IL-33 i.p. had heightened splenomegaly, more immune cells in the peritoneum including an expanded ST2L⁺ ILC2 population, increased eosinophilia in the spleen and peritoneum, and reduced sST2 in the circulation and peritoneum. In the spleen, lung, and liver of mice given IL-33, gene expression of both isoforms of ST2 was increased in Il13 ^-/- mice relative to WT. We confirmed fibroblasts to be an IL-13-responsive cell type that can regulate IL-33 activity through production of sST2. This study elucidates the important regulatory activity that IL-13 exerts on IL-33 through induction of IL-33 decoy receptor sST2 and through modulation of ST2L⁺ ILC2s.

Bee Venom Prevents Mucin 5AC Production through Inhibition of AKT and SPDEF Activation in Airway Epithelia Cells

IL-13 induces mucus metaplasia, which causes airway obstruction in asthma. Bee venom (BV) and its components have shown anti-inflammatory effects in allergic diseases such as atopic dermatitis and asthma. In this study, we investigated the effect of BV on IL-13-induced mucus metaplasia through activation of the signal transducer and activator of transcription (STAT6), and regulation of SAM-pointed domain containing Ets-like factor (SPDEF) and forkhead box A2 (FOXA2) in the airway epithelia cell line A549. In A549 cells, BV (1.0 µg/mL) inhibited IL-13 (10 ng/mL)-induced AKT phosphorylation, increase in SPDEF protein expression, and decrease in FOXA2 protein expression—but not STAT6 phosphorylation. BV also prevented the IL-13-induced increase in mucin 5AC (MUC5AC) mRNA and protein expression. Moreover, we observed that inhibition of phosphoinositide 3 kinase (PI3K)/AKT using LY294002 (50 µM) could reverse the alterations in FOXA2 and MUC5AC expression -by IL-13 and BV. However, LY294002 did not affect IL-13- and BV-induced changes in SPDEF expression. These findings indicate that BV inhibits MUC5AC production through the regulation of SPDEF and FOXA2. The inhibition of MUC5AC production through FOXA2 is mediated via the suppression of PI3K/AKT activation by BV. BV may be helpful in the prevention of mucus metaplasia in asthma.

Cellular and molecular mechanisms of allergic asthma

Asthma is a chronic disease of the airways, which affects more than 350 million people worldwide. It is the most common chronic disease in children, affecting at least 30 million children and young adults in Europe. Asthma is a complex, partially heritable disease with a marked heterogeneity. Its development is influenced both by genetic and environmental factors. The most common, as well as the most well characterized subtype of asthma is allergic eosinophilic asthma, which is characterized by a type 2 airway inflammation. The prevalence of asthma has substantially increased in industrialized countries during the last 60 years. The mechanisms underpinning this phenomenon are incompletely understood, however increased exposure to various environmental pollutants probably plays a role. Disease inception is thought to be enabled by a disadvantageous shift in the balance between protective and harmful lifestyle and environmental factors, including exposure to protective commensal microbes versus infection with pathogens, collectively leading to airway epithelial cell damage and disrupted barrier integrity. Epithelial cell-derived cytokines are one of the main drivers of the type 2 immune response against innocuous allergens, ultimately leading to infiltration of lung tissue with type 2 T helper (T_H2) cells, type 2 innate lymphoid cells (ILC2s), M2 macrophages and eosinophils. This review outlines the mechanisms responsible for the orchestration of type 2 inflammation and summarizes the novel findings, including but not limited to dysregulated epithelial barrier integrity, alarmin release and innate lymphoid cell stimulation.

The Role of Macrophages in the Development of Acute and Chronic Inflammatory Lung Diseases

Macrophages play an important role in the innate and adaptive immune responses of organ systems, including the lungs, to particles and pathogens. Cumulative results show that macrophages contribute to the development and progression of acute or chronic inflammatory responses through the secretion of inflammatory cytokines/chemokines and the activation of transcription factors in the pathogenesis of inflammatory lung diseases, such as acute lung injury (ALI), acute respiratory distress syndrome (ARDS), ARDS related to COVID-19 (coronavirus disease 2019, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)), allergic asthma, chronic obstructive pulmonary disease (COPD), and idiopathic pulmonary fibrosis (IPF). This review summarizes the functions of macrophages and their associated underlying mechanisms in the development of ALI, ARDS, COVID-19-related ARDS, allergic asthma, COPD, and IPF and briefly introduces the acute and chronic experimental animal models. Thus, this review suggests an effective therapeutic approach that focuses on the regulation of macrophage function in the context of inflammatory lung diseases.

Chronic rhinosinusitis with nasal polyps: mechanistic insights from targeting IL-4 and IL-13 via IL-4Rα inhibition with dupilumab

Introduction: Chronic rhinosinusitis with nasal polyps (CRSwNP) is a complex immunological upper airway disease . CRSwNP, particularly in Caucasians, often has a more distinct T2 inflammatory endotype. IL-4 and IL-13 are key upstream cytokines that help establish and sustain T2 inflammation as well as strongly influencing tissue remodeling. They have a shared signaling receptor IL-4Rα. An attractive and novel therapeutic approach is by way of blocking IL-4 and IL-13 simultaneously via inhibiting IL-4Rα. Dupilumab is a murine derived fully human monoclonal inhibitory antibody directed against IL-4Rα which thereby prevents IL-4/IL-13 cell signaling. Following successful Phase 3 studies dupilumab has become the first licensed biologic for treating CRSwNP. Areas covered: This review covers the essential immunology of CRSwNP in the context of IL-4 and IL-13 signaling via IL-4Rα. The potential mechanisms by which therapeutic improvements occur with dupilumab are evaluated. IL-4, IL-13, dupilumab and rhinosinusitis were used as the search terms in PubMed and Google Scholar through to August 2020. Expert commentary: Dupilumab has the potential to transform the care for patients with CRSwNP. It is essential that further studies are conducted promptly to identify disease-specific biomarkers and clinical traits to guide clinicians on best patient selection thereby ensuring optimal dupilumab outcomes.

IL-37 relieves allergic inflammation by inhibiting the CCL11 signaling pathway in a mouse model of allergic rhinitis

Allergic rhinitis (AR) is the allergic inflammation of immune cells in the nasal mucosa, caused by an abnormal T-cell response. Interleukin (IL)-37, a unique member of the IL-1 family with broad anti-inflammatory roles in various autoimmune diseases, participates in the immune regulation of AR. However, the regulatory mechanism of IL-37 in AR has remained elusive. In the present study, a mouse model of AR was established by treating mice with ovalbumin (OVA). Following systemic administration of IL-37, the effects of the cytokine on allergic symptoms were evaluated. The nasal mucosal infiltration of eosinophils was assessed by histopathological observation. The serum and nasal lavage fluid concentrations of immunoglobulin (Ig)E, IgG1, IgG2a, interferon (IFN)-γ, IL-4, IL-13, IL-17a and C-C motif cytokine ligand (CCL)11 were determined by ELISA. Treatment with OVA resulted in allergic symptoms, including enhanced eosinophil infiltration in the nasal mucosa, increased thickness of the nasal mucosa and increased levels of IgE, IgG1, IgG2a, IL-4, IL-13, IL-17a and CCL11, but the level of IFN-γ was indicated to decrease. After IL-37 treatment, the frequency of nasal rubbing and sneezing was reduced compared with that in the OVA group. IL-37 administration also decreased the number of eosinophils in the nasal mucosa and the thickness of the nasal mucosa, as well as the serum and nasal lavage fluid levels of IgE, IgG1, IgG2a, IL-4, IL-13, IL-17a and CCL11, but the level of IFN-γ decreased. In addition, the OVA-induced increases in histamine and substance P levels were reversed by IL-37 administration. CCL11 expression levels were correlated with the expression levels of IFN-γ, IL-4, IL-13, IL-17a, histamine and substance P. In conclusion, IL-37 alleviated the OVA-induced allergic symptoms and allergic inflammatory response by reducing the serum cytokine levels via decreasing CCL11 expression levels in mice.

Aryl Hydrocarbon Receptor Activation Downregulates IL-33 Expression in Keratinocytes via Ovo-Like 1

Background: IL-33, one of the IL-1 superfamily cytokines, has been shown to be associated with pruritus and inflammation in atopic dermatitis (AD). Furthermore, IL-33 production derived from keratinocytes reportedly has a crucial role in the development of AD; however, the mechanism of IL-33 expression has not been fully understood. Methods: We analyzed IL-33 expression in normal human epidermal keratinocytes (NHEKs) treated with IL-4. Results: IL-4 induced the upregulation of IL-33 expression in NHEKs. Based on the findings 1) that ovo-like 1 (OVOL1), a susceptible gene of AD, upregulates filaggrin (FLG) and loricrin (LOR) expression in NHEKs and 2) that reduced expression of FLG and LOR leads to production of IL-1 superfamily cytokines, we examined the involvement of OVOL1 in IL-33 expression in NHEKs. Knockdown of OVOL1 induced upregulation of IL-33 expression. Moreover, because Glyteer, an activator of aryl hydrocarbon receptor (AHR), reportedly upregulates OVOL1 expression, we examined whether treatment with Glyteer inhibited IL-33 expression in NHEKs. Treatment with Glyteer inhibited IL-4-induced upregulation of IL-33 expression, which was canceled by knockdown of either AHR or OVOL1. Conclusions: Activation of the AHR-OVOL1 axis inhibits IL-4-induced IL-33 expression, which could be beneficial for the treatment of AD.

Effect of sIL-13Rα2-Fc on the progression of rat tail intervertebral disc degeneration

BACKGROUND

The incidence of degenerative disc disease caused by intervertebral disc injury is increasing annually, seriously affecting the quality of life of patients and increasing the disease burden on society. The mechanisms of intervertebral disc degeneration include changes in extracellular matrix (ECM) deposition and tissue fibrosis. sIL-13Rα2-Fc potently inhibits interleukin (IL)-13, as well as blocks related cell signaling pathways and inhibits fibrosis in certain tissues. However, it is unknown whether sIL-13Rα2-Fc inhibits fibrosis in injured intervertebral discs and slows the process of degeneration. We hypothesized that sIL-13Rα2-Fc delays the progression of intervertebral disc degeneration by inhibiting intervertebral disc fibrosis and improving ECM deposition.

METHODS

A rat tail intervertebral disc degeneration model was established. Pathological changes in rat intervertebral disc tissue were observed by hematoxylin and eosin staining and Masson staining. Glycosaminoglycan (GAG), chondroitin sulfate (CS), keratan sulfate (KS), and hyaluronic acid (HA) contents were quantitatively analyzed by enzyme-linked immunosorbent assay. Type I and type II collagen expression levels were analyzed by reverse transcription-PCR and western blotting.

RESULTS

Hematoxylin and eosin staining and Masson staining revealed annulus fibrosus rupture, disordered arrangement, decreased nucleus pulposus tissue, and decreased collagen fiber in the rat intervertebral disc tissue. Following treatment with sIL-13Rα2-Fc, pathological changes in the rat intervertebral disc were reduced. Rat intervertebral disc tissue showed decreased GAG, CS-KS, and (HA) contents, increased type I collagen levels, and decreased type II collagen levels in degenerated intervertebral discs. sIL-13Rα2-Fc intervention increased the contents of GAG, CS, KS, and HA; inhibited the expression of type I collagen; and promoted the expression of type II collagen.

CONCLUSION

These results demonstrate that intervertebral disc degeneration is associated with tissue fibrosis. sIL-13Rα2-Fc can regulate type I and type II collagen expression levels by increasing GAG, CS, KS, and HA contents, thereby slowing the progression of intervertebral disc degeneration.

Retracted: The role of HOTAIR-induced downregulation of microRNA-126 and interleukin-13 in the development of bronchial hyperresponsiveness in neonates

Long noncoding RNAs, including HOTAIR, are involved in the pathogenesis of a wide range of diseases. This study aimed to explore the mechanism underlying the involvement of HOTAIR in neonatal bronchial hyperresponsiveness (BHR). A total of 105 newborns were recruited in this study to collect their peripheral blood mononuclear cell and serum samples, which were then divided into different genotype groups based on the genotypes of rs4759314, rs874945, and rs7958904. The real-time polymerase chain reaction, western blot analysis, computational analyses, and luciferase assays were performed to establish the regulatory relationships between the HOTAIR, microRNA-126 (miR-126), and interleukin-13 (IL-13). The level of HOTAIR, miR-126, and IL-13 among rs4759314 AA, AG, and GG groups, as well as among rs874945 GG, AG, and AA groups was similar. However, the level of HOTAIR was increased in the rs7958904 GG group, accompanied by a decreased level of miR-126 and IL-13. In addition, the level of airway responsiveness was comparable among rs4759314 AA, AG, and GG groups, as well as among rs874945 GG, AG, and AA groups. However, the airway responsiveness in the groups rs7958904 CG and CC was much stronger than that of the GG group. We also demonstrated that, by directly binding to miR-126, HOTAIR reduced the expression of miR-126, which in turn decreased the expression of IL-13. In summary, we demonstrated the role of HOTAIR-induced downregulation of miR-126 and IL-13 in the development of BHR in neonates.

The E3 ubiquitin ligase CHIP in normal cell function and in disease conditions

In eukaryotic cells, ubiquitination and proteasomal degradation is an essential mechanism for regulating protein functions. For example, critical signaling proteins play their roles by controlling different cellular functions. Once a signaling protein has been activated, its activity needs to be quickly downregulated by different mechanisms, including ubiquitination/proteasome regulation. Failure to regulate the activity or expression levels of these proteins may cause human diseases. Protein ubiquitination involves a cascade of biochemical processes and requires three types of ubiquitin enzymes: E1 activating enzyme, E2 conjugating enzyme, and E3 ligase. Among these enzymes, E3 ubiquitin ligases play a specific role in recognizing specific protein substrates. There are several structurally diverse groups of E3 ubiquitin ligases in eukaryotic cells, and one type of these E3 ligases is the U-box ubiquitin ligases. Carboxyl terminus of HSP70-interacting protein (CHIP) is a member of a family of U-box E3 ligases. It plays critical roles in multiple organs and tissues in the body. In this review article, we provide an update on some of the most recent discoveries about CHIP in normal physiological function and in disease.

Differential effects of inhaled R- and S-terbutaline in ovalbumin-induced asthmatic mice

Inhaled terbutaline is commercially available β₂-agonist which consists of equivalent amount of R- and S-enantiomer. In this study, we aimed to investigate the effects of single enantiomers of terbutaline and its racemate in an ovalbumin (OVA)-induced mouse model of asthma via. seven days inhalation and the potential mechanisms involved. In a standard experimental asthma model, BALB/c mice were sensitized and challenged with OVA. R-terbutaline (R-ter), S-terbutaline (S-ter) or racemic terbutaline (rac-ter) was given via. nose-only inhalation for one week. Airway responsiveness to methacholine was measured by the plethysmography in conscious mice. Eosinophils counts in blood and bronchoalveolar (BAL) fluid were determined. The OVA-sIgE in plasma and inflammatory cytokines and mediators in BAL fluid or lung tissue were analyzed by ELISA, qRT-PCR or western blotting. Airway inflammation and remodeling were evaluated with hematoxylin and eosin (HE), periodic acid-Schiff (PAS), and Masson staining. Drug distribution and deposition after inhalation were determined by LC-MS/MS. Our data showed that R-ter efficiently ameliorated asthma responses, including airway hyperresponsiveness, eosinophils influx and IL-5 in BALF, plasma OVA-sIgE and significantly reduced pulmonary inflammation, peribronchial smooth muscle layer thickness, goblet cell hyperplasia, and deposition of collagen fibers, as well as downregulation of p38 MAPK phosphorylation and NF-κB expression. Racemic mixture exhibited diminished effects while S-ter enhanced airway responsiveness to methacholine and exerted pro-asthmatic effects.

The receptor for advanced glycation end products is a critical mediator of type 2 cytokine signaling in the lungs

BACKGROUND

Asthma is estimated to effect more than 300 million persons worldwide, leading to nearly 250,000 deaths annually. The majority of patients with mild-to-severe asthma have what is deemed "type-2 high" asthma, which is driven by the prototypical type 2 cytokines IL-4, IL-5, and IL-13. Studies have indicated that the receptor for advanced glycation end products (RAGE) is a critical molecule in the pathogenesis of experimental asthma/allergic airway inflammation. More specifically, RAGE expressed on stromal cells, rather than hematopoietic cells, is critical to induction of asthma/allergic airway inflammation by driving type 2 inflammatory responses. However, the role of RAGE in directly mediating type 2 cytokine signaling has never been investigated.

OBJECTIVE

The goal of this study was to test the hypothesis that RAGE mediates type 2 cytokine-induced signal transduction, airway inflammation, and mucus metaplasia in the lungs.

METHODS

Wild-type (WT) and RAGE knockout (RAGE^-/-) mice, were intranasally administered rIL-5/rIL-13 or rIL-4 alone, and signal transducer and activator of transcription 6 (STAT6) signaling, airway inflammation, and mucus metaplasia were assessed. A RAGE small-molecule antagonist was used to determine the effects of pharmacologically inhibiting RAGE on type 2 cytokine-induced effects.

RESULTS

Administration of type 2 cytokines induced pronounced airway inflammation and mucus metaplasia in WT mice, which was nearly completely abrogated in RAGE^-/- mice. In addition, treatment with a RAGE-specific antagonist diminished the effects of type 2 cytokines in WT mice and in primary human bronchial epithelial cell cultures. Genetic ablation or pharmacologic inhibition of RAGE blocks the effects of IL-13 and IL-4 by inhibiting sustained STAT6 activation and downstream target gene expression in mice and in human bronchial epithelial cells.

CONCLUSIONS

This study is the first to indicate that RAGE is a critical component of type 2 cytokine signal transduction mechanisms, which is a driving force behind type 2-high asthma.

Genetic, Inflammatory, and Epithelial Cell Differentiation Factors Control Expression of Human Calpain-14

Eosinophilic esophagitis (EoE) is a chronic, food-driven allergic disease resulting in eosinophilic esophageal inflammation. We recently found that EoE susceptibility is associated with genetic variants in the promoter of CAPN14, a gene with reported esophagus-specific expression. CAPN14 is dynamically up-regulated as a function of EoE disease activity and after exposure of epithelial cells to interleukin-13 (IL-13). Herein, we aimed to explore molecular modulation of CAPN14 expression. We identified three putative binding sites for the IL-13-activated transcription factor STAT6 in the promoter and first intron of CAPN14. Luciferase reporter assays revealed that the two most distal STAT6 elements were required for the ∼10-fold increase in promoter activity subsequent to stimulation with IL-13 or IL-4, and also for the genotype-dependent reduction in IL-13-induced promoter activity. One of the STAT6 elements in the promoter was necessary for IL-13-mediated induction of CAPN14 promoter activity while the other STAT6 promoter element was necessary for full induction. Chromatin immunoprecipitation in IL-13 stimulated esophageal epithelial cells was used to further support STAT6 binding to the promoter of CAPN14 at these STAT6 binding sites. The highest CAPN14 and calpain-14 expression occurred with IL-13 or IL-4 stimulation of esophageal epithelial cells under culture conditions that allow the cells to differentiate into a stratified epithelium. This work corroborates a candidate molecular mechanism for EoE disease etiology in which the risk variant at 2p23 dampens CAPN14 expression in differentiated esophageal epithelial cells following IL-13/STAT6 induction of CAPN14 promoter activity.

Cyanidin-3-O-β-glucoside attenuates allergic airway inflammation by modulating the IL-4Rα-STAT6 signaling pathway in a murine asthma model

Cyanidin-3-O-β-glucoside (Cy-3-g), a typical and abundant monomer of anthocyanins, exhibits a variety of biological activities, such as anti-atherosclerosis, anti-obesity, and anticancer effects. However, to date little is known about its effects on asthma. This study aimed to investigate the efficacy of dietary Cy-3-g on allergic asthma in an animal model. BALB/c mice were sensitized and challenged with ovalbumin (OVA) to induce allergic asthma. The pathological changes of the lung tissues, type 2 helper (Th2)-associated cytokine production in bronchoalveolar lavage fluid (BALF), and the interleukin 4 receptor alpha (IL-4Rα)-signal transducer and activator of transcription 6 (STAT6) signaling pathway activities were assessed. We found that Cy-3-g significantly inhibited OVA-induced inflammatory cell infiltration and mucus hyper-production in lung tissues, reduced the production of interleukin 4 (IL-4), interleukin 5 (IL-5) and interleukin 13 (IL-13) in BALF. Furthermore, Cy-3-g effectively suppressed OVA-induced up-regulation of the IL-4Rα-STAT6 signaling pathway activity of the lung tissues. These results demonstrated that dietary Cy-3-g could attenuate allergic airway inflammation in a murine asthma model, and Cy-3-g might be used as an agent for asthma prevention and/or treatment in the future.

Human umbilical cord-derived mesenchymal stem cells ameliorate the enteropathy of food allergies in mice

Food allergy prevalence has steadily increased worldwide over the past decades and immunotherapeutic treatment strategies are gaining attention. Human umbilical cord-derived mesenchymal stem cells (hUC-MSCs) exhibit similar immune regulatory properties to bone marrow-derived MSCs. hUC-MCSs can be prepared with fewer ethical constraints and are potential candidates for allergic disorder therapies. The current study aimed to investigate potential antiallergic properties of hUC-MSCs in mice with ovalbumin (OVA)-induced food allergy. Administration of hUC-MSCs cells intraperitoneally combined with oral gavage of the culture medium significantly alleviated OVA-induced diarrhea symptoms. Additionally, this treatment significantly decreased IgE levels and the percentage of T helper 2 cells in the blood, which were increased in mice with OVA-induced food allergy. The mRNA levels of the inflammatory cytokines interleukin-4 and tumor necrosis factor-α, and inflammatory cell infiltration in mouse colons were significantly decreased in hUC-MSCs-treated animals compared with mice with OVA-induced food allergy. Goblet cells were detected in colons of allergy-induced mice and their numbers were reduced following treatment with hUC-MSCs. In addition, treatment with hUC-MSCs reestablished the gut flora. The results revealed that hUC-MSCs may have a potential application in food allergy therapy.

IL-37 inhibits IL-4/IL-13-induced CCL11 production and lung eosinophilia in murine allergic asthma

BACKGROUND

IL-37 is emerging as an anti-inflammatory cytokine, particularly in innate inflammation. However, the role of IL-37 in Th2-mediated allergic lung inflammation remains uncertain. We sought to determine the role and the underlying mechanisms of IL-37 in the development of house dust mites (HDM)-induced murine asthma model.

METHODS

We examined the effect of IL-37 administration during the sensitization or challenge phase on Th2-mediated allergic asthma induced by inhaled HDM. Cellular source of CCL11 and distribution of IL-37 receptors, IL-18Rα and IL-1R8, were determined in HDM-exposed lungs. Finally, we examined the effect of IL-37 on CCL11 production and STAT6 activation in different primary lung structural cell types upon IL-4/IL-13 stimulation.

RESULTS

IL-37 had no effect on HDM sensitization, but when administrated during the challenge phase, significantly attenuated pulmonary eosinophilia, CCL11 production, and airway hyper-reactivity (AHR). Interestingly, IL-37 treatment had no significant effects on lung infiltrating T cells and Th2 cytokine production. Intranasal co-administration of CCL11 reversed the inhibiting effect of IL-37 on HDM-induced pulmonary eosinophilia and AHR. Furthermore, we demonstrated that CCL11 was primarily expressed by fibroblasts and airway smooth muscle cells (AMSC), while IL-37 receptors by tracheobronchial epithelial cells (TEC). In vitro study showed that IL-37 inhibited IL-4/IL-13-induced STAT6 activation and CCL11 production by fibroblasts and AMSC, which was dependent on its direct action on TEC. Moreover, cell contact was required for the inhibitory effect of IL-37-treated TEC.

CONCLUSIONS

IL-37 attenuates HDM-induced asthma, possibly by inhibiting IL-4/IL-13-induced CCL11 production by fibroblasts and AMSC via its direct act on TEC.

Neuronal IL-4Rα modulates neuronal apoptosis and cell viability during the acute phases of cerebral ischemia

Ischemic stroke caused by an embolus or local thrombosis results in neural tissue damage (an infarct) in the territory of the occluded cerebral artery. Decades of studies have increased our understanding of the molecular events during cerebral infarction; however, translation of these discoveries to druggable targets for ischemic stroke treatment has been largely disappointing. Interleukin-4 (IL-4) is a multifunctional cytokine that exerts its cellular activities via the interleukin-4 receptor α (IL-4Rα). This cytokine receptor complex is associated with diverse immune and inflammatory responses. Recent studies have suggested a role of the cytokine IL-4 in long-term ischemic stroke recovery, involving immune cell activity. In contrast, the role of the receptor, IL-4Rα especially in the acute phase of infarction is unclear. In this study, we determined that IL-4Rα is expressed on neurons and that during the early phases of cerebral infarction (24 h) levels of this receptor are increased to regulate cellular apoptosis factors through activation of STAT6. In this context, we show a neuroprotective role for IL-4Rα in an in vivo surgical model of cerebral ischemia and in ex vivo brain slice explants, using both genetic knockout of this receptor and RNAi-mediated gene knockdown. IL-4Rα may therefore represent a novel target and pathway for therapeutic development in ischemic stroke.

March1 E3 Ubiquitin Ligase Modulates Features of Allergic Asthma in an Ovalbumin-Induced Mouse Model of Lung Inflammation

Membrane-associated RING-CH-1 (March1) is a member of the March family of E3 ubiquitin ligases. March1 downregulates cell surface expression of MHC II and CD86 by targeting them to lysosomal degradation. Given the key roles of MHC class II and CD86 in T cell activation and to get further insights into the development of allergic inflammation, we asked whether March1 deficiency exacerbates or attenuates features of allergic asthma in mice. Herein, we used an acute model of allergy to compare the asthmatic phenotype of March1-deficient and -sufficient mice immunized with ovalbumin (OVA) and later challenged by intranasal instillation of OVA in the lungs. We found that eosinophilic inflammation in airways and lung tissue was similar between WT and March1^-/- allergic mice, whereas neutrophilic inflammation was significant only in March1^-/- mice. Airway hyperresponsiveness as well as levels of IFN-γ, IL-13, IL-6, and IL-10 was lower in the lungs of asthmatic March1^-/- mice compared to WT, whereas lung levels of TNF-α, IL-4, and IL-5 were not significantly different. Interestingly, in the serum, levels of total and ova-specific IgE were reduced in March1-deficient mice as compared to WT mice. Taken together, our results demonstrate a role of March1 E3 ubiquitin ligase in modulating allergic responses.

Autophagy regulates DUOX1 localization and superoxide production in airway epithelial cells during chronic IL-13 stimulation

The airway epithelium is a broad interface with the environment, mandating well-orchestrated responses to properly modulate inflammation. Classically, autophagy is a homeostatic pathway triggered in response to external cellular stresses, and is elevated in chronic airway diseases. Recent findings highlight the additional role of autophagy in vesicle trafficking and protein secretion, implicating autophagy pathways in complex cellular responses in disease. Th2 cytokines, IL-13 and IL-4, are increased in asthma and other airway diseases contributing to chronic inflammation. Previously, we observed that IL-13 increases reactive oxygen species (ROS) in airway epithelial cells in an autophagy-dependent fashion. Here, we tested our hypothesis that autophagy is required for IL-13-mediated superoxide production via the NADPH oxidase DUOX1. Using a mouse model of Th2-mediated inflammation induced by OVA-allergen, we observed elevated lung amounts of IL-13 and IL-4 accompanied by increased autophagosome levels, determined by LC3BII protein levels and immunostaining. ROS levels were elevated and DUOX1 expression was increased 70-fold in OVA-challenged lungs. To address the role of autophagy and ROS in the airway epithelium, we treated primary human tracheobronchial epithelial cells with IL-13 or IL-4. Prolonged, 7-day treatment increased autophagosome formation and degradation, while brief activation had no effect. Under parallel culture conditions, IL-13 and IL-4 increased intracellular superoxide levels as determined by electron paramagnetic resonance (EPR) spectroscopy. Prolonged IL-13 activation increased DUOX1, localized at the apical membrane. Silencing DUOX1 by siRNA attenuated IL-13-mediated increases in superoxide, but did not reduce autophagy activities. Notably, depletion of autophagy regulatory protein ATG5 significantly reduced superoxide without diminishing total DUOX1 levels. Depletion of ATG5, however, diminished DUOX1 localization at the apical membrane. The findings suggest non-canonical autophagy activity regulates DUOX1-dependent localization required for intracellular superoxide production during Th2 inflammation. Thus, in chronic Th2 inflammatory airway disease, autophagy proteins may be responsible for persistent intracellular superoxide production.

Asthma and poly(ADP-ribose) polymerase inhibition: a new therapeutic approach

Asthma is a chronic lung disease affecting people of all ages worldwide, and it frequently begins in childhood. Because of its chronic nature, it is characterized by pathological manifestations, including airway inflammation, remodeling, and goblet cell hyperplasia. Current therapies for asthma, including corticosteroids and beta-2 adrenergic agonists, are directed toward relieving the symptoms of the asthmatic response, with poor effectiveness against the underlying causes of the disease. Asthma initiation and progression depends on the T helper (Th) 2 type immune response carried out by a complex interplay of cytokines, such as interleukin (IL) 4, IL5, and IL13, and the signal transducer and activator of transcription 6. Much of the data resulting from different laboratories support the role of poly(ADP-ribose) polymerase (PARP) 1 and PARP14 activation in asthma. Indeed, PARP enzymes play key roles in the regulation and progression of the inflammatory asthma process because they affect the expression of genes and chemokines involved in the immune response. Consistently, PARP inhibition achievable either upon genetic ablation or by using pharmacological agents has shown a range of therapeutic effects against the disease. Indeed, in the last two decades, several preclinical studies highlighted the protective effects of PARP inhibition in various animal models of asthma. PARP inhibitors showed the ability to reduce the overall lung inflammation acting with a specific effect on immune cell recruitment and through the modulation of asthma-associated cytokines production. PARP inhibition has been shown to affect the Th1–Th2 balance and, at least in some aspects, the airway remodeling. In this review, we summarize and discuss the steps that led PARP inhibition to become a possible future therapeutic strategy against allergic asthma.

Chi3l3: a potential key orchestrator of eosinophil recruitment in meningitis induced by Angiostrongylus cantonensis

BACKGROUND

Angiostrongylus cantonensis, an important foodborne parasite, can induce serious eosinophilic meningitis in non-permissive hosts, such as mouse and human. However, the characteristics and mechanisms of the infection are still poorly understood. This study sought to determine the key molecules and its underlying mechanism in inducing brain eosinophilic infiltration caused by Angiostrongylus cantonensis.

METHODS

Mathematical models were established for prediction of significantly changing genes and the functional associated protein with RNA-seq data in Angiostrongylus cantonensis infection. The expression level of Chi3l3, the predicted key molecule, was verified using Western blotting and real-time quantitative PCR. Critical cell source of Chi3l3 and its relationship with eosinophils were identified with flow cytometry, immunohistochemistry, and further verified by macrophage depletion using liposomal clodronate. The role of soluble antigens of Angiostrongylus cantonensis in eosinophilic response was identified with mice airway allergy model by intranasal administration of Alternaria alternate. The relationship between Chi3l3 and IL-13 was identified with flow cytometry, Western blotting, and Seahorse Bioscience extracellular flux analyzer.

RESULTS

We analyzed the skewed cytokine pattern in brains of Angiostrongylus cantonensis-infected mice and found Chi3l3 to be an important molecule, which increased sharply during the infection. The percentage of inflammatory macrophages, the main source of Chi3l3, also increased, in line with eosinophils percentage in the brain. Network analysis and mathematical modeling predirect a functional association between Chi3l3 and IL-13. Further experiments verified that the soluble antigen of Angiostrongylus cantonensis induce brain eosinophilic meningitis via aggravating a positive feedback loop between IL-13 and Chi3l3.

CONCLUSIONS

We present evidences in favor of a key role for macrophave-derived Chi3l3 molecule in the infection of Angiostrongylus cantonensis, which aggravates eosinophilic meningitis induced by Angiostrongylus cantonensis via a IL-13-mediated positive feedback loop. These reported results constitute a starting point for future research of angiostrongyliasis pathogenesis and imply that targeting chitinases and chitinase-like-proteins may be clinically beneficial in Angiostrongylus cantonensis-induced eosinophilic meningitis.

MicroRNA Profiling in Asthma: Potential Biomarkers and Therapeutic Targets

Asthma is a heterogeneous chronic inflammatory disorder in which different endotypes contribute to define clinical inflammatory phenotypes. MicroRNAs (miRNAs) are a group of minute, endogenous 22-25 nt RNA elements that join to particular mRNAs to reduce translation and increase messenger RNA degradation. miRNAs operate in post-transcriptional control and regulate physiological and pathological processes in several illnesses. The purpose of this work is to review and discuss the current knowledge about the function of miRNAs in asthma, focusing particularly on their biological properties, pathophysiologic actions, and possible use as markers and treatments for asthma.

High expression of IL-4R enhances proliferation and invasion of hepatocellular carcinoma cells

OBJECTIVE

In this study, we aimed to investigate the expression and function of interleukin-4 receptor (IL-4R) in hepatocellular carcinoma (HCC).

METHODS

We collected 40 pairs of human HCC and adjacent normal tissue specimens and examined the expression levels of IL-4R. After IL-4R knockdown in HCC cell lines, cell proliferation and invasion ability were examined. Cell cycle and apoptosis were analyzed by flow cytometry. The activity of multiple signaling pathways was examined by Western blot.

RESULTS

IL-4R was overexpressed in HCC tumors compared with adjacent normal control tissues and was associated with tumor differentiation status. IL-4R knockdown resulted in enhanced apoptosis, impaired proliferation and reduced invasion of HCC cells. Furthermore, IL-4R knockdown abolished IL-4-induced activation of the Janus Kinase 1 (JAK1)/signal transducer and activator of transcription 6 (STAT6) and JUN N-terminal kinase (JNK)/extracellular signal-regulated kinase 1/2 (ERK1/2) signaling pathways.

CONCLUSIONS

IL-4R plays an important role in regulating HCC cell survival and metastasis, and regulates the activity of the JAK1/STAT6 and JNK/ERK1/2 signaling pathways. We therefore suggest that IL-4/IL-4R may be a new therapeutic target for HCC.

Poly(ADP-Ribose)Polymerase-1 in Lung Inflammatory Disorders: A Review

Asthma, acute lung injury (ALI), and chronic obstructive pulmonary disease (COPD) are lung inflammatory disorders with a common outcome, that is, difficulty in breathing. Corticosteroids, a class of potent anti-inflammatory drugs, have shown less success in the treatment/management of these disorders, particularly ALI and COPD; thus, alternative therapies are needed. Poly(ADP-ribose)polymerases (PARPs) are the post-translational modifying enzymes with a primary role in DNA repair. During the last two decades, several studies have reported the critical role played by PARPs in a good of inflammatory disorders. In the current review, the studies that address the role of PARPs in asthma, ALI, and COPD have been discussed. Among the different members of the family, PARP-1 emerges as a key player in the orchestration of lung inflammation in asthma and ALI. In addition, PARP activation seems to be associated with the progression of COPD. Furthermore, PARP-14 seems to play a crucial role in asthma. STAT-6 and GATA-3 are reported to be central players in PARP-1-mediated eosinophilic inflammation in asthma. Interestingly, oxidative stress-PARP-1-NF-κB axis appears to be tightly linked with inflammatory response in all three-lung diseases despite their distinct pathophysiologies. The present review sheds light on PARP-1-regulated factors, which may be common or differential players in asthma/ALI/COPD and put forward our prospective for future studies.

IL-13 is a central mediator of chemical-induced airway hyperreactivity in mice

BACKGROUND

While the importance of the Th2 cytokine IL-13 as a central mediator of airway hyperreactivity (AHR) has been described in allergic protein-induced asthma, this has never been investigated in chemical-induced asthma.

OBJECTIVE

We examined the importance of IL-13 in a mouse model of chemical-induced AHR, using toluene-2,4-diisocyanate (TDI).

METHODS

In a first set-up, wild type (WT) and IL-13 knockout (KO) C57Bl/6 mice were dermally treated on days 1 and 8 with 1% TDI or vehicle (acetone/olive oil) on both ears. On day 15, mice received an intranasal instillation with 0.1% TDI or vehicle. In a second set-up, WT mice sensitized with 1% TDI or vehicle, received i.v. either anti-IL-13 or control antibody prior to the intranasal challenge.

RESULTS

TDI-sensitized and TDI-challenged WT mice showed AHR to methacholine, in contrast to TDI-sensitized and TDI-challenged IL-13 KO mice, which also showed lower levels of total serum IgE. TDI-sensitized and TDI-challenged IL-13 KO mice had lower numbers of T-cells in the auricular lymph nodes. TDI-treated WT mice, receiving anti-IL-13, showed no AHR, in contrast to those receiving control antibody, despite increased levels of IgE. Anti-IL-13 treatment in TDI-treated WT mice resulted in lower levels of serum IL-13, but did not induce changes in T- and B-cell numbers, and in the cytokine production profile.

CONCLUSION AND CLINICAL RELEVANCE

We conclude that IL-13 plays a critical role in the effector phase of chemical-induced, immune-mediated AHR. This implicates that anti-IL-13 treatment could have a beneficial effect in patients with this asthma phenotype.

New perspectives on the regulation of type II inflammation in asthma

Asthma is a chronic inflammatory disease of the lungs which has been thought to arise as a result of inappropriately directed T helper type-2 (Th2) immune responses of the lungs to otherwise innocuous inhaled antigens. Current asthma therapeutics are directed towards the amelioration of downstream consequences of type-2 immune responses (i.e. β-agonists) or broad-spectrum immunosuppression (i.e. corticosteroids). However, few approaches to date have been focused on the primary prevention of immune deviation. Advances in molecular phenotyping reveal heterogeneity within the asthmatic population with multiple endotypes whose varying expression depends on the interplay between numerous environmental factors and the inheritance of a broad range of susceptibility genes. The most common endotype is one described as "type-2-high" (i.e. high levels of interleukin [IL]-13, eosinophilia, and periostin). The identification of multiple endotypes has provided a potential explanation for the observations that therapies directed at typical Th2 cytokines (IL-4, IL-5, and IL-13) and their receptors have often fallen short when they were tested in a diverse group of asthmatic patients without first stratifying based on disease endotype or severity. However, despite the incorporation of endotype-dependent stratification schemes into clinical trial designs, variation in drug responses are still apparent, suggesting that additional genetic/environmental factors may be contributing to the diversity in drug efficacy. Herein, we will review recent advances in our understanding of the complex pathways involved in the initiation and regulation of type-2-mediated immune responses and their modulation by host factors (genetics, metabolic status, and the microbiome). Particular consideration will be given to how this knowledge could pave the way for further refinement of disease endotypes and/or the development of novel therapeutic strategies for the treatment of asthma .

Multiple functions of the E3 ubiquitin ligase CHIP in immunity

The carboxyl terminal of Hsp70-interacting protein (CHIP) is an E3 ubiquitin ligase that plays a pivotal role in the protein quality control system by shifting the balance of the folding-refolding machinery toward the degradative pathway. However, the precise mechanisms by which nonnative proteins are selected for degradation by CHIP either directly or indirectly via chaperone Hsp70 or Hsp90 are still not clear. In this review, we aim to provide a comprehensive model of the mechanism by which CHIP degrades its substrate in a chaperone-dependent or direct manner. In addition, through tight regulation of the protein level of its substrates, CHIP plays important roles in many physiological and pathological conditions, including cancers, neurological disorders, cardiac diseases, bone metabolism, immunity, and so on. Nonetheless, the precise mechanisms underlying the regulation of the immune system by CHIP are still poorly understood despite accumulating developments in our understanding of the regulatory roles of CHIP in both innate and adaptive immune responses. In this review, we also aim to provide a view of CHIP-mediated regulation of immune responses and the signaling pathways involved in the model described. Finally, we discuss the roles of CHIP in immune-related diseases.

MUC18 regulates IL-13-mediated airway inflammatory response

OBJECTIVE

To evaluate the effects of MUC18 on IL-13-mediated airway inflammatory responses in human airway epithelial cells and in mice.

MATERIALS

Primary normal human tracheobronchial epithelial (HTBE) cells, wild-type (WT) and Muc18 knockout (KO) mice, and mouse tracheal epithelial cells (mTECs) were utilized.

TREATMENT

Cultured HTBE cells treated with MUC18 siRNA or MUC18 expressing lentivirus were incubated with IL-13 (10 ng/mL) for 24 h. Mice were intranasally instilled with 500 ng of IL-13 for 3 days. mTECs were treated with IL-13 (10 ng/mL) for 3 days.

METHODS

PCR was used to measure mRNA expression. Western Blot and ELISAs were used to quantify protein expression. Cytospins of bronchoalveolar lavage (BAL) cells were used to obtain leukocyte differentials.

RESULTS

MUC18 siRNA reduced IL-13-mediated eotaxin-3 (183 ± 44 vs. 380 ± 59 pg/mL, p < 0.05), while MUC18 overexpression increased IL-13-mediated eotaxin-3 (95 ± 3 vs. 58 ± 3 pg/mL, p < 0.05) in HTBE cells. IL-13-treated Muc18 KO mice had a lower percentage of neutrophils in BAL than WT mice (25 ± 3 vs. 35 ± 3%, p = 0.0565).

CONCLUSIONS

These results implicate MUC18 as a potential enhancer of airway inflammation in a type 2 cytokine (e.g., IL-13) milieu.

Lyn regulates mucus secretion and MUC5AC via the STAT6 signaling pathway during allergic airway inflammation

Hypersecretion of mucus is an important component of airway remodeling and contributes to the mucus plugs and airflow obstruction associated with severe asthma phenotypes. Lyn has been shown to down-regulate allergen-induced airway inflammation. However, the role of Lyn in mucin gene expression remains unresolved. In this study, we first demonstrate that Lyn overexpression decreased the mucus hypersecretion and levels of the muc5ac transcript in mice exposed to ovalbumin (OVA). Lyn overexpression also decreased the infiltration of inflammatory cells and the levels of IL-13 and IL-4 in OVA-challenged airways. Whereas Lyn knockdown increased the IL-4 or IL-13-induced MUC5AC transcript and protein levels in the human bronchial epithelial cell line, 16HBE, Lyn overexpression decreased IL-4- or IL-13-induced MUC5AC transcript and protein levels. Overexpression of Lyn also decreased the expression and phosphorylation of STAT6 in OVA-exposed mice, whereas Lyn knockdown increased STAT6 and MUC5AC levels in 16HBE cells. Finally, chromatin immunoprecipitation analysis confirmed that Lyn overexpression decreased the binding of STAT6 to the promoter region of Muc5ac in mice exposed to OVA. Collectively, these findings demonstrated that Lyn overexpression ameliorated airway mucus hypersecretion by down-regulating STAT6 and its binding to the MUC5AC promoter.

The Role of Cytokines in the Development of Atherosclerosis

Atherosclerosis contributes to the development of many cardiovascular diseases, which remain the leading cause of death in developed countries. Atherosclerosis is a chronic inflammatory disease of large and medium-sized arteries. It is caused by dyslipidemia and mediated by both innate and adaptive immune responses. Inflammation is a key factor at all stages of atherosclerosis progression. Cells involved in pathogenesis of atherosclerosis were shown to be activated by soluble factors, cytokines, that strongly influence the disease development. Pro-inflammatory cytokines accelerate atherosclerosis progression, while anti-inflammatory cytokines ameliorate the disease. In this review, we discuss the latest findings on the role of cytokines in the development and progression of atherosclerosis.

Role of Transcription Factors in Pulmonary Artery Smooth Muscle Cells: An Important Link to Hypoxic Pulmonary Hypertension

Hypoxia, namely a lack of oxygen in the blood, induces pulmonary vasoconstriction and vasoremodeling, which serve as essential pathologic factors leading to pulmonary hypertension (PH). The underlying molecular mechanisms are uncertain; however, pulmonary artery smooth muscle cells (PASMCs) play an essential role in hypoxia-induced pulmonary vasoconstriction, vasoremodeling, and PH. Hypoxia causes oxidative damage to DNAs, proteins, and lipids. This damage (oxidative stress) modulates the activity of ion channels and elevates the intracellular calcium concentration ([Ca²⁺]_i, Ca²⁺ signaling) of PASMCs. The oxidative stress and increased Ca²⁺ signaling mutually interact with each other, and synergistically results in a variety of cellular responses. These responses include functional and structural abnormalities of mitochondria, sarcoplasmic reticulum, and nucleus; cell contraction, proliferation, migration, and apoptosis, as well as generation of vasoactive substances, inflammatory molecules, and growth factors that mediate the development of PH. A number of studies reveal that various transcription factors (TFs) play important roles in hypoxia-induced oxidative stress, disrupted PAMSC Ca²⁺ signaling and the development and progress of PH. It is believed that in the pathogenesis of PH, hypoxia facilitates these roles by mediating the expression of multiple genes. Therefore, the identification of specific genes and their transcription factors implicated in PH is necessary for the complete understanding of the underlying molecular mechanisms. Moreover, this identification may aid in the development of novel and effective therapeutic strategies for PH.

Traumatic brain injury and subsequent glioblastoma development: Review of the literature and case reports

BACKGROUND

Previous reports have proposed an association between traumatic brain injury (TBI) and subsequent glioblastoma (GBM) formation.

METHODS

We used literature searches and radiographic evidence from two patients to assess the possibility of a link between TBI and GBM.

RESULTS

Epidemiological studies are equivocal on a possible link between brain trauma and increased risk of malignant glioma formation. We present two case reports of patients with GBM arising at the site of prior brain injury.

CONCLUSION

The hypothesis that TBI may predispose to gliomagenesis is disputed by several large-scale epidemiological studies, but supported by some. Radiographic evidence from two cases presented here suggest that GBM formed at the site of brain injury. We propose a putative pathogenesis model that connects post-traumatic inflammation, stem and progenitor cell transformation, and gliomagenesis.