IL-13 receptor alpha 2: a regulator of IL-13 and IL-4 signal transduction in primary human fibroblasts

Tumor diagnosis using carbon-based quantum dots: Detection based on the hallmarks of cancer

Carbon-based quantum dots (CQDs) have been shown to have promising application value in tumor diagnosis. Their use, however, is severely hindered by the complicated nature of the nanostructures in the CQDs. Furthermore, it seems impossible to formulate the mechanisms involved using the inadequate theoretical frameworks that are currently available for CQDs. In this review, we re-consider the structure-property relationships of CQDs and summarize the current state of development of CQDs-based tumor diagnosis based on biological theories that are fully developed. The advantages and deficiencies of recent research on CQDs-based tumor diagnosis are thus explained in terms of the manifestation of nine essential changes in cell physiology. This review makes significant progress in addressing related problems encountered with other nanomaterials.

ADAM33's Role in Asthma Pathogenesis: An Overview

Asthma is a complex chronic respiratory disease characterized by airway hyperresponsiveness, inflammation, and obstruction. Many genes have been identified as associated with asthma but none with such substantial significance as the ADAM33 gene due to its role in airway remodeling and bronchial hyperresponsiveness. This review summarizes the current knowledge on the genetic and functional aspects of ADAM33 in asthma pathogenesis. We highlight its genetic variants associated with asthma susceptibility and severity, as well as the functional effects of ADAM33 on airway remodeling, smooth muscle cell proliferation, and its interplay with environmental factors. Additionally, we discuss the potential clinical implications of ADAM33 as a therapeutic target for asthma management.

Engineering the IL-4/IL-13 axis for targeted immune modulation

The structurally and functionally related interleukin-4 (IL-4) and IL-13 cytokines play pivotal roles in shaping immune activity. The IL-4/IL-13 axis is best known for its critical role in T helper 2 (Th2) cell-mediated Type 2 inflammation, which protects the host from large multicellular pathogens, such as parasitic helminth worms, and regulates immune responses to allergens. In addition, IL-4 and IL-13 stimulate a wide range of innate and adaptive immune cells, as well as non-hematopoietic cells, to coordinate various functions, including immune regulation, antibody production, and fibrosis. Due to its importance for a broad spectrum of physiological activities, the IL-4/IL-13 network has been targeted through a variety of molecular engineering and synthetic biology approaches to modulate immune behavior and develop novel therapeutics. Here, we review ongoing efforts to manipulate the IL-4/IL-13 axis, including cytokine engineering strategies, formulation of fusion proteins, antagonist development, cell engineering approaches, and biosensor design. We discuss how these strategies have been employed to dissect IL-4 and IL-13 pathways, as well as to discover new immunotherapies targeting allergy, autoimmune diseases, and cancer. Looking ahead, emerging bioengineering tools promise to continue advancing fundamental understanding of IL-4/IL-13 biology and enabling researchers to exploit these insights to develop effective interventions.

Tralokinumab Effectively Disrupts the IL-13/IL-13Rα1/IL-4Rα Signaling Complex but Not the IL-13/IL-13Rα2 Complex

Tralokinumab, a fully human mAb specifically targeting the IL-13 cytokine, has demonstrated clinical efficacy and safety in patients with moderate-to-severe atopic dermatitis. Tralokinumab binds IL-13 with high affinity, which prevents the interaction of IL-13 with IL-13Rα1 and subsequent signaling. Similarly, tralokinumab-bound IL-13 cannot bind to IL-13Rα2, a proposed decoy receptor that is reported to bind IL-13 with extraordinarily high affinity. It has however not been fully elucidated to what extent tralokinumab interferes with the endogenous regulation of IL-13 through IL-13Rα2. In this mechanistic study, we used biophysical, biochemical, and cellular assays to investigate the effect of tralokinumab on the interaction between IL-13 and IL-13Rα1 and IL-13Rα2, respectively, as well as the effects on IL-13Rα2-mediated IL-13 internalization. We demonstrate that IL-13Rα2 binds IL-13 with exceptionally high affinity and that tralokinumab is unable to displace IL-13 from IL-13Rα2. In contrast to this, tralokinumab is able to disrupt the IL-13/IL-13Rα1 and IL-13Rα1/IL-13/IL-4Rα complex. Furthermore, we demonstrate that whereas the IL-13/tralokinumab complex is unable to bind IL-13Rα2, any IL-13 that is not bound by tralokinumab (i.e., free IL-13) can be bound by IL-13Rα2 and subsequently internalized, regardless of the presence of tralokinumab. In summary, our study indicates that tralokinumab does not interfere with endogenous IL-13Rα2-mediated regulation of free IL-13.

Vertical sleeve gastrectomy associates with airway hyperresponsiveness in a murine model of allergic airway disease and obesity

Introduction

Asthma is a chronic airway inflammatory disease marked by airway inflammation, remodeling and hyperresponsiveness to allergens. Allergic asthma is normally well controlled through the use of beta-2-adrenergic agonists and inhaled corticosteroids; however, a subset of patients with comorbid obesity experience resistance to currently available therapeutics. Patients with asthma and comorbid obesity are also at a greater risk for severe disease, contributing to increased risk of hospitalization. Bariatric surgery improves asthma control and airway hyperresponsiveness in patients with asthma and comorbid obesity, however, the underlying mechanisms for these improvements remain to be elucidated. We hypothesized that vertical sleeve gastrectomy (VSG), a model of metabolic surgery in mice, would improve glucose tolerance and airway inflammation, resistance, and fibrosis induced by chronic allergen challenge and obesity.

Methods

Male C57BL/6J mice were fed a high fat diet (HFD) for 13 weeks with intermittent house dust mite (HDM) allergen administration to induce allergic asthma, or saline as control. At week 11, a subset of mice underwent VSG or Sham surgery with one week recovery. A separate group of mice did not undergo surgery. Mice were then challenged with HDM or saline along with concurrent HFD feeding for 1-1.5 weeks before measurement of lung mechanics and harvesting of tissues, both of which occurred 24 hours after the final HDM challenge. Systemic and pulmonary cytokine profiles, lung histology and gene expression were analyzed.

Results

High fat diet contributed to increased body weight, serum leptin levels and development of glucose intolerance for both HDM and saline treatment groups. When compared to saline-treated mice, HDM-challenged mice exhibited greater weight gain. VSG improved glucose tolerance in both saline and HDM-challenged mice. HDM-challenged VSG mice exhibited an increase in airway hyperresponsiveness to methacholine when compared to the non-surgery group.

Discussion

The data presented here indicate increased airway hyperresponsiveness in allergic mice undergoing bariatric surgery.

Targeting of the Interleukin-13 Receptor (IL-13R)α2 Expressing Prostate Cancer by a Novel Hybrid Lytic Peptide

The IL-13Rα2 cell surface receptor is highly expressed in tumours such as prostate cancer. In this report, we evaluated the hypothesis that prostate cancer cells with enhanced IL-13Rα2 expression are a suitable target for the hybrid lytic peptide (Pep-1-Phor21) peptide, which is generated by fusing the IL-13Rα2 specific ligand (Pep-1) and a cell membrane disrupting lytic peptide (Phor21). The expression of IL-13Rα2 mRNA and protein in prostate cancer tissues and cell lines was assessed via real-time PCR (RT-PCR) and immunoblotting. The effect of Pep-1-Phor21 on the viability of prostate cancer cells grown in monolayers (2D) and microtissue spheroids (3D) was assessed via CellTox green cytotoxic assay. IL-13Rα2 expression and Pep-1-Phor21-mediated killing were also determined in the cells treated with epigenetic regulators (Trichostatin A (TSA) and 5-aza-2 deoxycytidine (5-Aza-dC)). The hybrid lytic peptide cytotoxic activity correlated with the expression of IL-13Rα2 in prostate cancer cell lines cultured as monolayers (2D) or 3D spheroids. In addition, TSA or 5-Aza-dC treatment of prostate cancer cells, particularly those with low expression of IL-13Rα2, enhanced the cells' sensitivity to the lytic peptide by increasing IL-13Rα2 expression. These results demonstrate that the Pep-1-Phor21 hybrid lytic peptide has potent and selective anticancer properties against IL-13Rα2-expressing prostate cancer cells.

Keratinocytes activated by IL-4/IL-13 express IL-2Rγ with consequences on epidermal barrier function

Atopic dermatitis (AD) is a Th2-type inflammatory disease characterized by an alteration of epidermal barrier following the release of IL-4 and IL-13. These cytokines activate type II IL-4Rα/IL-13Rα1 receptors in the keratinocyte. Whilst IL-2Rγ, that forms type I receptor for IL-4, is only expressed in haematopoietic cells, recent studies suggest its induction in keratinocytes, which questions about its role. We studied expression of IL-2Rγ in keratinocytes and its role in alteration of keratinocyte function and epidermal barrier. IL-2Rγ expression in keratinocytes was studied using both reconstructed human epidermis (RHE) exposed to IL-4/IL-13 and AD skin. IL-2Rγ induction by type II receptor has been analyzed using JAK inhibitors and RHE knockout (KO) for IL13RA1. IL-2Rγ function was investigated in RHE KO for IL2RG. In RHE, IL-4/IL-13 induce expression of IL-2Rγ at the mRNA and protein levels. Its mRNA expression is also visualized in keratinocytes of lesional AD skin. IL-2Rγ expression is low in RHE treated with JAK inhibitors and absent in RHE KO for IL13RA1. Exposure to IL-4/IL-13 alters epidermal barrier, but this alteration is absent in RHE KO for IL2RG. A more important induction of IL-13Rα2 is reported in RHE KO for IL2RG than in not edited RHE. These results demonstrate IL-2Rγ induction in keratinocytes through activation of type II receptor. IL-2Rγ is involved in the alteration of the epidermal barrier and in the regulation of IL-13Rα2 expression. Observation of IL-2Rγ expression by keratinocytes inside AD lesional skin suggests a role for this receptor subunit in the disease.

Innate lymphoid cells in depression: Current status and perspectives

The recent discovery of innate lymphoid cells (ILCs) has provided new insights into our understanding of the pathogenesis of many disease conditions with immune dysregulation. Type 1 innate lymphoid cells (ILC1s) induce type I immunity and are characterized by the expression of signature cytokine IFN-γ and the master transcription factor T-bet; ILC2s stimulate type II immune responses and are defined by the expression of signature cytokines IL-5 and IL-13, and transcription factors ROR-α and GATA3; ILC3s requires the transcription factor RORγt and produce IL-22 and IL-17. ILCs are largely tissue-resident and are enriched at barrier surfaces of the mammalian body. Increasing evidence shows that inflammation is involved in the pathogenesis of depression. Although few studies have directly investigated the role of ILCs in depression, several studies have examined the levels of cytokines produced by ILCs in depressed subjects. This review summarizes the potential roles of ILCs in depression. A better understanding of the biology of ILCs may lead to the development of new therapeutic strategies for the management of depression.

Atopic dermatitis: pathomechanisms and lessons learned from novel systemic therapeutic options

Atopic dermatitis (AD) is a chronic, heterogenous, inflammatory skin disorder associated with a high skin-related health burden, typically starting in childhood and often persisting into adulthood. AD is characterized by a wide range of clinical phenotypes, reflecting multiple underlying pathophysiological mechanisms and interactions between genetics, immune system dysregulation, and environmental factors. In this review, we describe the diverse cellular and molecular mechanisms involved in AD, including the critical role of T cell-driven inflammation, primarily via T helper (Th) 2- and Th17-derived cytokines, many of which are mediated by the Janus kinase (JAK) signaling pathway. These local inflammatory processes interact with sensory neuronal pathways, contributing to the clinical manifestations of AD, including itch, pain, and sleep disturbance. The recent elucidation of the molecular pathways involved in AD has allowed treatment strategies to evolve from broad-acting systemic immunosuppressive therapies to more targeted agents, including JAK inhibitors and cytokine-specific biologic agents. Evidence from the clinical development of these targeted therapies has reinforced and expanded our understanding of the pathophysiological mechanisms underlying AD and holds promise for individualized treatment strategies tailored to specific AD subtypes.

Innate immune regulates cutaneous sensory IL-13 receptor alpha 2 to promote atopic dermatitis

The clinical significance and regulators of IL-13Rα2 in itch and atopic dermatitis (AD) remain unclear. To identify disease-driven regulatory circuits of IL-13Rα2, transcriptomic/pathological analysis was performed in skin from patients with AD, psoriasis, healthy subjects, and murine AD model. Functionality was investigated in sensory neurons, keratinocytes and animal model, by using knockdown (KD), calcium imaging, RNA-seq, cytokine arrays, pharmacological assays, and behavioural investigations. In our study, an upregulated IL-13Rα2 expression was revealed in skin of AD patients, but not psoriasis, in a disease activity-dependent manner. In cultured human keratinocytes, IL-13 increased IL-13Rα2 transcription levels, and this were downregulated by IL-13Rα1KD. IL-13Rα2KD reduced transcription levels of EDNRA, CCL20, CCL26. In contrast, sensory neuron-derived IL-13Rα2 was upregulated by TLR2 heterodimer agonists, Pam3CSK4 and FSL-1. In a mouse cheek model, pre-administration of Pam3CSK4 and FSL-1 enhanced IL-13-elicited scratching behaviour. Consistently, in cultured sensory neurons Pam3CSK4 enhanced IL-13-elicted calcium transients, increased number of responders, and orchestrated chemerin, CCL17 and CCL22 release. These release was inhibited by IL-13Rα2KD. Collectively, IL-13 regulates keratinocyte-derived IL-13Rα2 and TLR2 to modulate neuronal IL-13Rα2, thereby promoting neurogenic inflammation and exacerbating AD and itch. Thus, the cutaneous IL-13-IL-13Rα2 and neuronal TLR2-IL-13Rα2 pathway represent important targets to treat AD and itch.

Engineered nasal cartilage for the repair of osteoarthritic knee cartilage defects

[Figure: see text].

Design considerations of an IL13Rα2 antibody-drug conjugate for diffuse intrinsic pontine glioma

Diffuse intrinsic pontine glioma (DIPG), a rare pediatric brain tumor, afflicts approximately 350 new patients each year in the United States. DIPG is noted for its lethality, as fewer than 1% of patients survive to five years. Multiple clinical trials involving chemotherapy, radiotherapy, and/or targeted therapy have all failed to improve clinical outcomes. Recently, high-throughput sequencing of a cohort of DIPG samples identified potential therapeutic targets, including interleukin 13 receptor subunit alpha 2 (IL13Rα2) which was expressed in multiple tumor samples and comparably absent in normal brain tissue, identifying IL13Rα2 as a potential therapeutic target in DIPG. In this work, we investigated the role of IL13Rα2 signaling in progression and invasion of DIPG and viability of IL13Rα2 as a therapeutic target through the use of immunoconjugate agents. We discovered that IL13Rα2 stimulation via canonical ligands demonstrates minimal impact on both the cellular proliferation and cellular invasion of DIPG cells, suggesting IL13Rα2 signaling is non-essential for DIPG progression in vitro. However, exposure to an anti-IL13Rα2 antibody-drug conjugate demonstrated potent pharmacological response in DIPG cell models both in vitro and ex ovo in a manner strongly associated with IL13Rα2 expression, supporting the potential use of targeting IL13Rα2 as a DIPG therapy. However, the tested ADC was effective in most but not all cell models, thus selection of the optimal payload will be essential for clinical translation of an anti-IL13Rα2 ADC for DIPG.

Attenuation of Dupuytren's fibrosis via targeting of the STAT1 modulated IL-13Rα1 response

Fibrotic disorders represent common complex disease pathologies that are therapeutically challenging. Inflammation is associated with numerous fibrotic pathogeneses; however, its role in the multifaceted mechanisms of fibrosis remains unclear. IL-13 is implicated in aberrant responses involved in fibrotic disease, and we aimed to understand its role in the inflammatory processes of a common fibrotic disorder, Dupuytren's disease. We demonstrated T-cells produced IFN-g, which induced IL-13 secretion from mast cells and up-regulated IL-13Ra1 on fibroblasts, rendering them more reactive to IL-13. Consequently, diseased myofibroblasts demonstrated enhanced fibroproliferative effects upon IL-13 stimulation. We established IFN-g and IL-13 responses involved STAT dependent pathways, and STAT targeting (tofacitinib) could inhibit IL-13 production from mast cells, IL-13Ra1 up-regulation in fibroblasts and fibroproliferative effects of IL-13 on diseased myofibroblasts. Accordingly, utilizing Dupuytren's as an accessible human model of fibrosis, we propose targeting STAT pathways may offer previously unidentified therapeutic approaches in the management of fibrotic disease.

Transcriptional regulation of the IL-13Rα2 gene in human lung fibroblasts

Interleukin (IL)-13 is a type 2 cytokine with important roles in allergic diseases, asthma, and tissue fibrosis. Its receptor (R) α1 is primarily responsible for the biological actions of this cytokine, while Rα2 possesses a decoy function which can block IL-13 signaling. Although the expression of Rα2 is known to be subject to modulation, information about its transcriptional regulation is limited. In this study, we sought to expand the understanding of transcriptional control of Rα2 in lung fibroblasts. We confirmed previous reports that IL-13 elicited modest induction of Rα2 in normal adult human lung fibroblasts, but found that prostaglandin E2 (PGE2) and fibroblast growth factor 2 (FGF-2) -mediators known to influence fibroblast activation in tissue fibrosis but not previously investigated in this regard - led to a much greater magnitude of Rα2 induction. Although both PGE2 (via protein kinase A) and FGF-2 (via protein kinase B, also known as AKT) depended on activation of cAMP-responsive element-binding protein (CREB) for induction of Rα2 expression, they nevertheless demonstrated synergy in doing so, likely attributable to their differential utilization of distinct transcriptional start sites on the Rα2 promoter. Our data identify CREB activation via PGE2 and FGF-2 as a previously unrecognized molecular controller of Rα2 gene induction and provide potential new insights into strategies for therapeutic manipulation of this endogenous brake on IL-13 signaling.

Interleukin-13: Targeting an underestimated cytokine in atopic dermatitis

Atopic dermatitis (AD) is a common inflammatory skin condition that has traditionally been considered a paradigmatic type 2 immunity (T2)-driven disease. Interleukin (IL)-4 and IL-13 are both pivotal cytokines involved in the generation of allergic diseases. Currently, besides dupilumab, which blocks the binding of both cytokines to their receptors, a number of new pharmacologic entities have been designed to target both T2 cytokines and/or their receptors and/or receptor-associated signal transduction machinery such as Janus kinases. Recently, IL-13 has been suggested to be the key T2 cytokine driving inflammation in the periphery, while IL-4 may merely have a central effect. There is increasing evidence that this concept holds true for the inflammatory reaction underlying AD, where IL-13 is overexpressed locally and has a significant impact on skin biology, including the recruitment of inflammatory cells, the alteration of the skin microbiome, and the decrease in the epidermal barrier function. This review provides an update on the role of IL-13 in AD and discusses the different strategies aimed at interfering with its biologic activity as well as their potential in a precision medicine approach in the management of AD.

Anti-IL-13Rα2 therapy promotes recovery in a murine model of inflammatory bowel disease

There continues to be a major need for more effective inflammatory bowel disease (IBD) therapies. IL-13Rα2 is a decoy receptor that binds the cytokine IL-13 with high affinity and diminishes its STAT6-mediated effector functions. Previously, we found that IL-13Rα2 was necessary for IBD in mice deficient in the anti-inflammatory cytokine IL-10. Here, we tested for the first time a therapeutic antibody specifically targeting IL-13Rα2. We also used the antibody and Il13ra2^-/- mice to dissect the role of IL-13Rα2 in IBD pathogenesis and recovery. Il13ra2^-/- mice were modestly protected from induction of dextran sodium sulfate (DSS)-induced colitis. Following a 7-day recovery period, Il13ra2^-/- mice or wild-type mice administered the IL-13Rα2-neutralizing antibody had significantly improved colon health compared to control mice. Neutralizing IL-13Rα2 to increase IL-13 bioavailability promoted resolution of IBD even if neutralization occurred only during recovery. To link our observations in mice to a large human cohort, we conducted a phenome-wide association study of a more active variant of IL-13 (R130Q) that has reduced affinity for IL-13Rα2. Human subjects carrying R130Q reported a lower risk for Crohn's disease. Our findings endorse moving anti-IL-13Rα2 into preclinical drug development with the goal of accelerating recovery and maintaining remission in Crohn's disease patients.

Interleukin-13 in the pathogenesis of pulmonary artery hypertension

Background

Interleukin (IL)-13 is a regulatory factor of tissue remodeling and is involved in the pathogenesis of pulmonary artery hypertension (PAH). However, the implications of IL-13 in PAH remains uncertain. This article aims to describe the current knowledge on production and function of IL-13 and its receptors in the mechanisms of PAH.

Content

The study materials of this article were based on comprehensive literature retrieval of publications of IL-13 in PAH. These study materials were carefully reviewed, analyzed and discussed.

Summary

IL-13 levels in blood and lung tissue were elevated in both animal models of PAH and patients with PAH in comparison to non-PAH controls. Types I and II IL-13 receptors participate in pulmonary artery remodeling through signal transducer and activator of transcription (STAT)6 or through phosphatidylinositol 3-kinase (PI3K), STAT3 and mitogen activated protein kinase (MAPK) pathways. Oxidant, arginase 2 (Arg2) and hypoxia-inducible factor 1α are involved in the proliferation of pulmonary artery smooth muscle cells.

Outlook

Types I and II IL-13 receptors play an important role in the IL-13 signaling by STAT6 via Janus kinase kinases, and by PI3K, STAT3 and MAPK pathways, respectively. Alternative pathways, including oxidant, Arg2 and hypoxia-inducible factor 1α might be also involved in the pathological process of PAH development. Investigational therapies by inflammatory suppression or thrombolytic and anticoagulant agents could inhibit intimal hyperplasia of the pulmonary arteries and suppress pulmonary vasculature remodeling. Drug research and development oriented by this hypothesis would confer benefits to the treatment of PAH.

The controversial role of mast cells in fibrosis

Fibrosis is a medical condition characterized by an excessive deposition of extracellular matrix compounds such as collagen in tissues. Fibrotic lesions are present in many diseases and can affect all organs. The excessive extracellular matrix accumulation in these conditions can often have serious consequences and in many cases be life-threatening. A typical event seen in many fibrotic conditions is a profound accumulation of mast cells (MCs), suggesting that these cells can contribute to the pathology. Indeed, there is now substantialv evidence pointing to an important role of MCs in fibrotic disease. However, investigations from various clinical settings and different animal models have arrived at partly contradictory conclusions as to how MCs affect fibrosis, with many studies suggesting a detrimental role of MCs whereas others suggest that MCs can be protective. Here, we review the current knowledge of how MCs can affect fibrosis.

IL-13 signaling through IL-13 receptor α2 mediates airway epithelial wound repair

Asthma is an airway inflammatory disease characterized by epithelial barrier dysfunction and airway remodeling. Interleukin-13 (IL-13) is a pleiotropic cytokine shown to contribute to features of airway remodeling. We have previously demonstrated that IL-13 is an important mediator of normal airway epithelial repair and health. The role of IL-13 signaling via its receptor subunits (IL-13Rα1/IL-4Rα and IL-13Rα2) in airway epithelial repair and restoration of intact barrier function is not well understood and was investigated in this study using in vitro models. The blocking of IL-13 signaling via IL-13Rα2 significantly reduced airway epithelial repair by 24 h post-mechanical wounding in 1HAEo^- cells. Expression and release of repair-mediating growth factor, heparin-binding epidermal growth factor (EGF)-like growth factor (HB-EGF), and subsequent activation of EGF receptor (EGFR) were also significantly reduced in response to wounding when IL-13Rα2 was blocked. Our data support that IL-13 signals via IL-13Rα2 to mediate normal airway epithelial repair via HB-EGF-dependent activation of EGFR. In human donor lung tissues, we observed that airway epithelium of asthmatics expressed significantly decreased levels of IL-13Rα2 and increased levels of IL-13Rα1 compared with nonasthmatics. Dysregulated expression of IL-13 receptor subunits in the airways of asthmatics may thus contribute to the epithelial barrier dysfunction observed in asthma.-Yang, S. J., Allahverdian, S., Saunders, A. D. R., Liu, E., Dorscheid, D. R. IL-13 signaling through IL-13 receptor α2 mediates airway epithelial wound repair.

Role of IL-13Rα2 in modulating IL-13-induced MUC5AC and ciliary changes in healthy and CRSwNP mucosa

BACKGROUND

The IL-13 receptor α2 (IL-13Rα2) is a receptor for IL-13 which has conflicting roles in mediating IL-13 responses in the lower airway, with little known about its impact on upper airway diseases. We sought to investigate the expression of IL-13 receptors, IL-13Rα1 and IL-13Rα2, in chronically inflamed nasal epithelium, and explore IL-13-induced signaling pathways in an in vitro model of human nasal epithelial cells (hNECs).

METHODS

The protein and mRNA expression levels of IL-13 and its receptors in nasal biopsies of patients with nasal polyps (NP) and healthy controls were evaluated. We investigated goblet cell stimulation with mucus hypersecretion induced by IL-13 (10 ng/mL, 72 hours) treatment in hNECs using a pseudostratified epithelium in air-liquid interface (ALI) culture.

RESULTS

There were significant increases in IL-13, IL-13Rα1, and IL-13Rα2 mRNA and protein levels in NP epithelium with healthy controls as baseline. MUC5AC mRNA positively correlated with IL-13Rα2 (r = .5886, P = .002) but not with IL-13Rα1 in primary hNECs. IL-13 treatment resulted in a significant increase in mRNA and protein levels of IL-13Rα2 only in hNECs. IL-13 treatment induced an activation of extracellular signal-regulated kinases (ERK)1/2 and an upregulation of C-JUN, where the IL-13-induced effects on hNECs could be attenuated by ERK1/2 inhibitor (50 μmol/L) or dexamethasone (10^-4 -10^-7  mol/L) treatment.

CONCLUSIONS

IL-13Rα2 has a potential role in IL-13-induced MUC5AC and ciliary changes through ERK1/2 signal pathway in the nasal epithelium. IL-13Rα2 may contribute to airway inflammation and aberrant remodeling which are the main pathological features of CRSwNP.

Differential effects of peptidoglycan on colorectal tumors and intestinal tissue post-pelvic radiotherapy

Immediate medical intervention is required after pelvic tumor radiotherapy to protect the radiosensitive intestine and also to mitigate tumor growth. Toll-like receptors (TLRs) have been shown to promote tissue repair processes. Here, we analyzed the effect observed upon combining the TLR2 agonist, peptidoglycan (PGN), with radiation therapy on tumors as well as intestinal tissue, both in vitro and in vivo. In contrast to radiotherapy alone, PGN when combined with ionizing radiation (IR) elicited enhanced antitumor effects and also reduced the IR-induced intestinal damage. Mechanistic studies showed that PGN first induced an IL13 response in the irradiated intestine, but was decreased in tumor cell models screened by Th1/Th2 FlowCytomix assay and validated by the application of IL13 and anti-IL13 neutralizing antibodies. Next, PGN stimulated Akt3, but not Akt1/2, as was verified by AKT1/2/3 plasmid transfection assay and in AKT1/2/3 knockout mice in vivo. Akt3 expression was inhibited in 20 μg/mL PGN-treated tumor cells and in 1.5 mg/kg PGN-treated mouse tumor models. However, Akt3 was raised via IL13 in the irradiated intestine and human intestinal cell line after the same treatment. Finally, PGN activated mTOR via IL13/AKT3 in the intestine and restored intestinal structure and function. As an adjuvant to radiotherapy, PGN inhibited tumorigenesis by suppression of mTOR activity. To summarize, the IL13/AKT3/mTOR pathway was lessened in PGN-treated irradiated tumors but was raised in the normal intestine tissue. This distinct effect of PGN on normal and tumor tissues during pelvic radiotherapy suggests that PGN may be a promising adjuvant therapy to radiation.

IL-13 and idiopathic pulmonary fibrosis: Possible links and new therapeutic strategies

The recent advances in the knowledge of immunological aspects of many pulmonary diseases, allowed to identify cells, biological functions, cytokines, and receptors that are preferentially involved in each disease. This is the case of asthma, where IL-13 (together with IL-4) is recognized as a central mediator. The role of IL-13 is strictly related, via complex signaling pathways, to eosinophil recruitment and activation, to mucus secretion, periostin generation and to fibrogenic processes (which are part of the remodeling process). These peculiar roles of IL-13 have suggested the hypothesis of its role in Idiopathic Pulmonary Fibrosis, and consequently of its antagonists in the treatment of such disease. We review herein the immunological roles of IL-13 in asthma and IPF, and the currently ongoing attempts to treat IPF by IL-13 antagonism strategies.

Interleukin 4 and interleukin 13 downregulate the lipopolysaccharide-mediated inflammatory response by human gestation-associated tissues

Inflammation is a key feature of preterm and term labor. Proinflammatory mediators are produced by gestation-associated tissues in response to pathogen-associated molecular patterns and damage-associated molecular patterns. Interleukin (IL)4, IL10, and IL13 are anti-inflammatory cytokines with potential as anti-inflammatory therapies to prevent preterm birth. The objective of this study was to determine if IL4 and IL13 exert anti-inflammatory effects on lipopolysaccharide (LPS)-stimulated production of proinflammatory cytokines produced by human term gestation-associated tissues (placenta, choriodecidua, and amnion). Both IL4 and IL13 reduced LPS-stimulated IL1B and macrophage inflammatory protein1A; this effect diminished with delay to exposure to either cytokine. There was no effect on LPS-stimulated prostaglandin production. Interleukin 4 receptor alpha (IL4RA) was expressed throughout the placenta, choriodecidua, and amnion, and the inhibitory effects of IL4 and IL13 were IL4RA dependent. Combined IL4 and IL13 did not enhance the anti-inflammatory potential of either cytokine; however, a combination of IL4 and IL10 had a greater anti-inflammatory effect than either cytokine alone. These findings demonstrate that human term gestation-associated tissues are responsive to the anti-inflammatory cytokines IL4 and IL13, which could downregulate LPS-induced cytokine production in these tissues. Anti-inflammatory cytokines might offer an adjunct to existing therapeutics to prevent adverse obstetric outcome.

IL-13 is a therapeutic target in radiation lung injury

Pulmonary fibrosis is a potentially lethal late adverse event of thoracic irradiation. Prior research indicates that unrestrained TGF-β1 and/or type 2 cytokine-driven immune responses promote fibrosis following radiation injury, but the full spectrum of factors governing this pathology remains unclear. Interleukin 13 (IL-13) is a key factor in fibrotic disease associated with helminth infection, but it is unclear whether it plays a similar role in radiation-induced lung fibrosis. Using a mouse model, we tested the hypothesis that IL-13 drives the progression of radiation-induced pulmonary fibrosis. Irradiated lungs from wild-type c57BL/6NcR mice accumulated alternatively-activated macrophages, displayed elevated levels of IL-13, and extensive fibrosis, whereas IL-13 deficient mice were resistant to these changes. Furthermore, plasma from irradiated wild-type mice showed a transient increase in the IL-13 saturated fraction of the circulating decoy receptor IL-13Rα2. Finally, we determined that therapeutic neutralization of IL-13, during the period of IL-13Rα2 saturation was sufficient to protect mice from lung fibrosis. Taken together, our results demonstrate that IL-13 is a major regulator of radiation-induced lung injury and demonstrates that strategies focusing on IL-13 may be useful in screening for timely delivery of anti-IL-13 therapeutics.

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.

Soluble ADAM33 initiates airway remodeling to promote susceptibility for allergic asthma in early life

Asthma is a chronic inflammatory airways disease that usually begins in early life and involves gene-environment interactions. Although most asthma exhibits allergic inflammation, many allergic individuals do not have asthma. Here, we report how the asthma gene a disintegrin and metalloprotease 33 (ADAM33) acts as local tissue susceptibility gene that promotes allergic asthma. We show that enzymatically active soluble ADAM33 (sADAM33) is increased in asthmatic airways and plays a role in airway remodeling, independent of inflammation. Furthermore, remodeling and inflammation are both suppressed in Adam33-null mice after allergen challenge. When induced in utero or added ex vivo, sADAM33 causes structural remodeling of the airways, which enhances postnatal airway eosinophilia and bronchial hyperresponsiveness following subthreshold challenge with an aeroallergen. This substantial gene-environment interaction helps to explain the end-organ expression of allergic asthma in genetically susceptible individuals. Finally, we show that sADAM33-induced airway remodeling is reversible, highlighting the therapeutic potential of targeting ADAM33 in asthma.

Loss of ADAM33 suppresses airway remodeling and allergic inflammation in mice, suggesting the therapeutic potential of targeting ADAM33 in asthma.

IL-27 enhances innate immunity of human pulmonary fibroblasts and epithelial cells through upregulation of TLR4 expression

Lung tissue cells play an active role in the pathogenesis of pulmonary inflammatory diseases by releasing a variety of cytokines and chemokines. However, how lung tissue cells respond to microbial stimuli during pulmonary infections remains unclear. In this study, we found that patients with community-acquired pneumonia displayed increased IL-27 levels in bronchoalveolar lavage fluid and serum. We subsequently examined the immunopathological mechanisms for the activation of primary human lung fibroblasts and bronchial epithelial cells by IL-27. We demonstrated that IL-27 priming enhanced LPS-induced production of IL-6 and IL-8 from lung fibroblasts and bronchial epithelia cells via upregulating Toll-like receptor-4 (TLR4) expression. IL-27 upregulated TLR4 expression in lung fibroblasts through activation of Janus-activated kinase (JAK) and Jun NH2-terminal kinase (JNK) signaling pathways, and inhibition of the JAK pathway could partially decrease IL-27-induced TLR4 expression, while inhibition of JNK pathway could completely suppress IL-27-induced TLR4 expression. Our data suggest that IL-27 modulates innate immunity of lung tissue cells through upregulating TLR4 expression during pulmonary infections.

Bayesian modeling suggests that IL-12 (p40), IL-13 and MCP-1 drive murine cytokine networks in vivo

Background

Cytokine-hormone network deregulations underpin pathologies ranging from autoimmune disorders to cancer, but our understanding of these networks in physiological/pathophysiological states remains patchy. We employed Bayesian networks to analyze cytokine-hormone interactions in vivo using murine lactation as a dynamic, physiological model system.

Results

Circulatory levels of estrogen, progesterone, prolactin and twenty-three cytokines were profiled in post partum mice with/without pups. The resultant networks were very robust and assembled about structural hubs, with evidence that interleukin (IL)-12 (p40), IL-13 and monocyte chemoattractant protein (MCP)-1 were the primary drivers of network behavior. Network structural conservation across physiological scenarios coupled with the successful empirical validation of our approach suggested that in silico network perturbations can predict in vivo qualitative responses. In silico perturbation of network components also captured biological features of cytokine interactions (antagonism, synergy, redundancy).

Conclusion

These findings highlight the potential of network-based approaches in identifying novel cytokine pharmacological targets and in predicting the effects of their exogenous manipulation in inflammatory/immune disorders.

Electronic supplementary material

The online version of this article (doi:10.1186/s12918-015-0226-3) contains supplementary material, which is available to authorized users.

c-Jun N-terminal kinase and Akt signalling pathways regulating tumour necrosis factor-α-induced interleukin-32 expression in human lung fibroblasts: implications in airway inflammation

Airway inflammatory diseases such as chronic obstructive pulmonary disease (COPD) and asthma are associated with elevated expression of interleukin-32 (IL-32), a recently described cytokine that appears to play a critical role in inflammation. However, so far, the regulation of pulmonary IL-32 production has not been fully established. We examined the expression of IL-32 by tumour necrosis factor-α (TNF-α) in primary human lung fibroblasts. Human lung fibroblasts were cultured in the presence or absence of TNF-α and/or other cytokines/Toll-like receptor (TLR) ligands or various signalling molecule inhibitors to analyse the expression of IL-32 by quantitative RT-PCR and ELISA. Next, activation of Akt and c-Jun N-terminal kinase (JNK) signalling pathways was investigated by Western blot. Interleukin-32 mRNA of four spliced isoforms (α, β, γ and δ) was up-regulated upon TNF-α stimulation, which was associated with a significant IL-32 protein release from TNF-α-activated human lung fibroblasts. The combination of interferon-γ and TNF-α induced enhanced IL-32 release in human lung fibroblasts, whereas IL-4, IL-17A, IL-27 and TLR ligands did not alter IL-32 release in human lung fibroblasts either alone, or in combination with TNF-α. Furthermore, the activation of Akt and JNK pathways regulated TNF-α-induced IL-32 expression in human lung fibroblasts, and inhibition of the Akt and JNK pathways was able to suppress the increased release of IL-32 to nearly the basal level. These data suggest that TNF-α may be involved in airway inflammation via the induction of IL-32 by activating Akt and JNK signalling pathways. Therefore, the TNF-α/IL-32 axis may be a potential therapeutic target for airway inflammatory diseases.

Type 2 cytokines: mechanisms and therapeutic strategies

Type 2 immune responses are defined by the cytokines interleukin-4 (IL-4), IL-5, IL-9 and IL-13, which can either be host protective or have pathogenic activity. Type 2 immunity promotes antihelminth immunity, suppresses type 1-driven autoimmune disease, neutralizes toxins, maintains metabolic homeostasis, and regulates wound repair and tissue regeneration pathways following infection or injury. Nevertheless, when type 2 responses are dysregulated, they can become important drivers of disease. Type 2 immunity induces a complex inflammatory response characterized by eosinophils, mast cells, basophils, type 2 innate lymphoid cells, IL-4-and/or IL-13-conditioned macrophages and T helper 2 (TH2) cells, which are crucial to the pathogenesis of many allergic and fibrotic disorders. As chronic type 2 immune responses promote disease, the mechanisms that regulate their maintenance are thought to function as crucial disease modifiers. This Review discusses the many endogenous negative regulatory mechanisms that antagonize type 2 immunity and highlights how therapies that target some of these pathways are being developed to treat type 2-mediated disease.

Type 2 cytokines: mechanisms and therapeutic strategies

Type 2 immune responses are defined by the cytokines interleukin-4 (IL-4), IL-5, IL-9 and IL-13, which can either be host protective or have pathogenic activity. Type 2 immunity promotes antihelminth immunity, suppresses type 1-driven autoimmune disease, neutralizes toxins, maintains metabolic homeostasis, and regulates wound repair and tissue regeneration pathways following infection or injury. Nevertheless, when type 2 responses are dysregulated, they can become important drivers of disease. Type 2 immunity induces a complex inflammatory response characterized by eosinophils, mast cells, basophils, type 2 innate lymphoid cells, IL-4-and/or IL-13-conditioned macrophages and T helper 2 (TH2) cells, which are crucial to the pathogenesis of many allergic and fibrotic disorders. As chronic type 2 immune responses promote disease, the mechanisms that regulate their maintenance are thought to function as crucial disease modifiers. This Review discusses the many endogenous negative regulatory mechanisms that antagonize type 2 immunity and highlights how therapies that target some of these pathways are being developed to treat type 2-mediated disease.

Interleukin-13 is overexpressed in cutaneous T-cell lymphoma cells and regulates their proliferation

Cutaneous T-cell lymphomas (CTCLs) primarily affect skin and are characterized by proliferation of mature CD4(+) T-helper cells. The pattern of cytokine production in the skin and blood is considered to be of major importance for the pathogenesis of CTCLs. Abnormal cytokine expression in CTCLs may be responsible for enhanced proliferation of the malignant cells and/or depression of the antitumor immune response. Here we show that interleukin-13 (IL-13) and its receptors IL-13Rα1 and IL-13Rα2 are highly expressed in the clinically involved skin of CTCL patients. We also show that malignant lymphoma cells, identified by the coexpression of CD4 and TOX (thymus high-mobility group box), in the skin and blood of CTCL patients produce IL-13 and express both receptors. IL-13 induces CTCL cell growth in vitro and signaling through the IL-13Rα1. Furthermore, antibody-mediated neutralization of IL-13 or soluble IL-13Rα2 molecules can lead to inhibition of tumor-cell proliferation, implicating IL-13 as an autocrine factor in CTCL. Importantly, we established that IL-13 synergizes with IL-4 in inhibiting CTCL cell growth and that blocking the IL-4/IL-13 signaling pathway completely reverses tumor-cell proliferation. We conclude that IL-13 and its signaling mediators are novel markers of CTCL malignancy and potential therapeutic targets for intervention.

Significance of interleukin-13 receptor alpha 2-targeted glioblastoma therapy

Glioblastoma multiforme (GBM) remains one of the most lethal primary brain tumors despite surgical and therapeutic advancements. Targeted therapies of neoplastic diseases, including GBM, have received a great deal of interest in recent years. A highly studied target of GBM is interleukin-13 receptor α chain variant 2 (IL13Rα2). Targeted therapies against IL13Rα2 in GBM include fusion chimera proteins of IL-13 and bacterial toxins, nanoparticles, and oncolytic viruses. In addition, immunotherapies have been developed using monoclonal antibodies and cell-based strategies such as IL13Rα2-pulsed dendritic cells and IL13Rα2-targeted chimeric antigen receptor-modified T cells. Advanced therapeutic development has led to the completion of phase I clinical trials for chimeric antigen receptor-modified T cells and phase III clinical trials for IL-13-conjugated bacterial toxin, with promising outcomes. Selective expression of IL13Rα2 on tumor cells, while absent in the surrounding normal brain tissue, has motivated continued study of IL13Rα2 as an important candidate for targeted glioma therapy. Here, we review the preclinical and clinical studies targeting IL13Rα2 in GBM and discuss new advances and promising applications.

Rhinovirus-16 induced release of IP-10 and IL-8 is augmented by Th2 cytokines in a pediatric bronchial epithelial cell model

Background

In response to viral infection, bronchial epithelial cells increase inflammatory cytokine release to activate the immune response and curtail viral replication. In atopic asthma, enhanced expression of Th2 cytokines is observed and we postulated that Th2 cytokines may augment the effects of rhinovirus-induced inflammation.

Methods

Primary bronchial epithelial cell cultures from pediatric subjects were treated with Th2 cytokines for 24 h before infection with RV16. Release of IL-8, IP-10 and GM-CSF was measured by ELISA. Infection was quantified using RTqPCR and TCID₅₀. Phosphatidyl inositol 3-kinase (PI3K) and P38 mitogen activated protein kinase (MAPK) inhibitors and dexamethasone were used to investigate differences in signaling pathways.

Results

The presence of Th2 cytokines did not affect RV replication or viral titre, yet there was a synergistic increase in IP-10 release from virally infected cells in the presence of Th2 cytokines. Release of IL-8 and GM-CSF was also augmented. IP-10 release was blocked by a PI3K inhibitor and IL-8 by dexamethasone.

Conclusion

Th2 cytokines increase release of inflammatory cytokines in the presence of rhinovirus infection. This increase is independent of effects of virus replication. Inhibition of the PI3K pathway inhibits IP-10 expression.

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.

Interleukin-13 and its receptors in colorectal cancer (Review)

Interleukin (IL)-13 is an immunoregulatory cytokine secreted by numerous immune cells. Its functions are similar to those of IL-4 and they share a common receptor. This cytokine has been included in recent studies on human tumors and malignant diseases, evoking a scientific interest to investigate the role of IL-13 and its receptors as novel biomarkers and targets for therapy. Colorectal cancer is one of the most common human malignancies, its prognosis is not promising and the efficacy of molecular-targeted therapy has not been established. This review summarizes the currently available data on the role of IL-13 and its receptors in colorectal cancer, including the signaling pathways involved in mediating the effects of IL-13, the role of IL-13 and/or its receptors in the prediction of cancer and several drugs targeting IL-13 or its receptors that are currently under evaluation.

The innate antiviral response upregulates IL-13 receptor α2 in bronchial fibroblasts

BACKGROUND

IL-13 is key mediator of allergic inflammation in asthmatic patients. We have previously shown that the decoy receptor IL-13 receptor (IL-13R) α2 attenuates responses of fibroblasts to IL-13. Because the expression of IL-13Rα2 can be regulated by IFN-γ, a type II interferon, we hypothesized that innate antiviral responses characterized by type I interferon expression can also induce IL-13Rα2 expression.

OBJECTIVE

We sought to induce an innate antiviral response in primary fibroblasts using exposure to double-stranded RNA (dsRNA) and to examine the expression and function of IL-13Rα2.

METHODS

Primary human fibroblasts were cultured from endobronchial biopsy specimens obtained from healthy or asthmatic volunteers and challenged with dsRNA. Upregulation of IL-13Rα2 mRNA was measured by using real-time quantitative PCR, and cell-surface IL-13Rα2 protein expression was measured by using fluorescence-activated cell sorting. Eotaxin release was determined by means of ELISA.

RESULTS

Direct treatment with IFN-β led to an upregulation of IL-13Rα2. Exposure to dsRNA rapidly induced IFN-β mRNA in fibroblasts, and this was followed by significant induction of IL-13Rα2 mRNA and cell-surface protein expression, which was dependent on de novo protein synthesis. A neutralizing antibody to the IFN-α/β receptor blocked cell-surface expression of IL-13Rα2 in the presence of dsRNA. Pretreatment of fibroblasts with dsRNA led to attenuation of IL-13-stimulated eotaxin production. However, the presence of an IL-13Rα2 neutralizing antibody restored IL-13-stimulated eotaxin production in dsRNA-treated cells.

CONCLUSION

IFN-β induces IL-13Rα2 expression, leading to a consequential suppression of responsiveness to IL-13. These data suggest cross-talk between TH1 and TH2 pathways and point to an immunomodulatory role for IL-13Rα2 in human bronchial fibroblasts during viral infection.

Monoclonal antibodies for asthma and chronic obstructive pulmonary disease

INTRODUCTION

In asthma and chronic obstructive pulmonary disease (COPD), the inflammation in the airways cannot always be controlled with conventional therapies, such as inhaled corticosteroids. Addition of more specific anti-inflammatory therapies, such as monoclonal antibodies, against inflammation pathways might improve the disease outcome.

AREAS COVERED

This review individually discusses the major inflammation pathways and their potential blocking monoclonal antibodies in asthma and COPD.

EXPERT OPINION

The current use of omalizumab in asthma provides a good example on the potential therapeutic role of monoclonal antibodies in both asthma and COPD. There are many other monoclonal antibodies which are currently investigated as possible therapies in these diseases. The identification of the disease subsets in which such antibodies might exert the maximum benefit opens the door for personalized medicine and for targeted biological therapy in asthma and COPD.

The role of SCCA1 in asthma related physiological events in the airway epithelium and the effect of promoter variants on asthma and gene function

BACKGROUND

Even though the systemic level of SCCA1, a serine protease inhibitor, was shown to be elevated in asthma, its physiological role is unknown.

OBJECTIVE

We sought to determine the effect of SCCA1 on apoptosis, cytokine expression and mucus production by A549 cells and define the effect of promoter variants on gene expression and association with asthma.

METHODS

SCCA levels were measured by ELISA. Promoter variants were determined by direct sequencing. 442 asthmatic children and 191 controls were genotyped by RFLP. The functional effect of the polymorphisms was assessed in transient transfection experiments using reporter constructs. A transcription factor ELISA was used for differential binding of GATA proteins to the variant region. The effects of SCCA1 on cytokine synthesis, mucus production and apoptosis were determined in A549 cells transfected with SCCA1 pcDNA vector. MUC5AC expression in A549 cells was determined with RT-PCR.

RESULTS

SCCA1 protein level was significantly higher in asthmatic children compared to healthy controls. Four polymorphisms SCCA1 promoter that were in linkage disequilibrium were associated with skin test positivity in asthmatic children and showed higher promoter activity and higher binding of GATA-2 and GATA-3 after IL-4 + IL-13 stimulation. IL-6, IL-8 levels were significantly higher in cells transfected with SCCA1 whereas RANTES increased only after IL-4 stimulation. Transfection of A549 cells with SCCA1 resulted in decreased MUC5AC expression and conferred protection against apoptosis.

CONCLUSION

Our results showed that SCCA1 has diverse effects on many of the cellular events that characterize asthma and its role extends beyond protease inhibition.

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

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

Accelerated and progressive and lethal liver fibrosis in mice that lack interleukin (IL)-10, IL-12p40, and IL-13Rα2

BACKGROUND & AIMS

Progressive fibrosis contributes to the morbidity of several chronic diseases; it typically develops slowly, so the mechanisms that control its progression and resolution have been difficult to model. The proteins interleukin (IL)-10, IL-12p40, and IL-13Rα2 regulate hepatic fibrosis following infection with the helminth parasite Schistosoma mansoni. We examined whether these mediators interact to slow the progression of hepatic fibrosis in mice with schistosomiasis.

METHODS

IL-10(-/-), IL-12/23(p40)(-/-), and IL-13Rα2(-/-) mice were crossed to generate triple knockout (TKO) mice. We studied these mice to determine whether the simultaneous deletion of these 3 negative regulators of the immune response accelerated mortality from liver fibrosis following infection with S mansoni.

RESULTS

Induction of inflammation by S mansoni, liver fibrosis, and mortality increased greatly in TKO mice compared with wild-type mice; 100% of the TKO mice died by 10 weeks after infection. Morbidity and mortality were associated with the development of portal hypertension, hepatosplenomegaly, gastrointestinal bleeding, ascites, thrombocytopenia, esophageal and gastric varices, anemia, and increased levels of liver enzymes, all features of advanced liver disease. IL-10, IL-12p40, and IL-13Rα2 reduced the production and activity of the profibrotic cytokine IL-13. A neutralizing antibody against IL-13 reduced the morbidity and mortality of the TKO mice following S mansoni infection.

CONCLUSIONS

IL-10, IL-12p40, and IL-13Rα2 act cooperatively to suppress liver fibrosis in mice following infection with S mansoni. This model rapidly reproduces many of the complications observed in patients with advanced cirrhosis, so it might be used to evaluate the efficacy of antifibrotic reagents being developed for schistosomiasis or other fibrotic diseases associated with a T-helper 2 cell-mediated immune response.

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.

Mapping mouse IL-13 binding regions using structure modeling, molecular docking, and high-density peptide microarray analysis

Interleukin-13 is a Th2-associated cytokine responsible for many pathological responses in allergic asthma including mucus production, inflammation, and extracellular matrix remodeling. In addition, IL-13 is required for immunity to many helminth infections. IL-13 signals via the type-II IL-4 receptor, a heterodimeric receptor of IL-13Rα1 and IL-4Rα, which is also used by IL-4. IL-13 also binds to IL-13Rα2, but with much higher affinity than the type-II IL-4 receptor. Binding of IL-13 to IL-13Rα2 has been shown to attenuate IL-13 signaling through the type-II IL-4 receptor. However, molecular determinants that dictate the specificity and affinity of mouse IL-13 for the different receptors are largely unknown. Here, we used high-density overlapping peptide arrays, structural modeling, and molecular docking methods to map IL-13 binding sequences on its receptors. Predicted binding sequences on mouse IL-13Rα1 and IL-13Rα2 were in agreement with the reported human IL-13 receptor complex structures and site-directed mutational analysis. Novel structural differences were identified between IL-13 receptors, particularly at the IL-13 binding interface. Notably, additional binding sites were observed for IL-13 on IL-13Rα2. In addition, the identification of peptide sequences that are unique to IL-13Rα1 allowed us to generate a monoclonal antibody that selectively binds IL-13Rα1. Thus, high-density peptide arrays combined with molecular docking studies provide a novel, rapid, and reliable method to map cytokine-receptor interactions that may be used to generate signaling and decoy receptor-specific antagonists.

Coxiella burnetii, the agent of Q fever, replicates within trophoblasts and induces a unique transcriptional response

Q fever is a zoonosis caused by Coxiella burnetii, an obligate intracellular bacterium typically found in myeloid cells. The infection is a source of severe obstetrical complications in humans and cattle and can undergo chronic evolution in a minority of pregnant women. Because C. burnetii is found in the placentas of aborted fetuses, we investigated the possibility that it could infect trophoblasts. Here, we show that C. burnetii infected and replicated in BeWo trophoblasts within phagolysosomes. Using pangenomic microarrays, we found that C. burnetii induced a specific transcriptomic program. This program was associated with the modulation of inflammatory responses that were shared with inflammatory agonists, such as TNF, and more specific responses involving genes related to pregnancy development, including EGR-1 and NDGR1. In addition, C. burnetii stimulated gene networks organized around the IL-6 and IL-13 pathways, which both modulate STAT3. Taken together, these results revealed that trophoblasts represent a protective niche for C. burnetii. The activation program induced by C. burnetii in trophoblasts may allow bacterial replication but seems unable to interfere with the development of normal pregnancy. Such pathophysiologocal processes should require the activation of immune placental cells associated with trophoblasts.

IL-13Rα2 has a protective role in a mouse model of cutaneous inflammation

IL-13 is expressed in lesions of atopic dermatitis (AD) and has been associated with increased disease severity. IL-13 has two cognate receptors: IL-13Rα1 and IL-13Rα2. Although IL-13Rα2 expression is known to be induced in response to IL-13 in keratinocytes, its function in AD has never been evaluated. We characterized the loss of skin barrier function and the development of cutaneous inflammation in IL-13Rα2-null versus wild-type BALB/c mice following an epicutaneous allergen-sensitization/challenge model that shares similarities with human AD. Mice lacking IL-13Rα2 had significantly increased transepidermal water loss, cutaneous inflammation, peripheral eosinophilia, and IgG1 and IgE levels compared with wild-type mice. The rate of resolution of the cutaneous inflammation was not significantly altered in the IL-13Rα2-null mice. IL-13 induced expression of IL-13Rα2 in keratinocyte cell lines and primary human keratinocytes. Depletion of IL-13Rα2 in a keratinocyte cell line resulted in increased STAT6 signaling in response to IL-13. In conclusion, IL-13Rα2 serves a protective role in the pathogenesis of allergic inflammation and loss of skin barrier function in a mouse model of AD, suggesting that it may be an important endogenous regulator of IL-13-induced cutaneous inflammation in humans.