The primary binding subunit of the human interleukin-4 receptor is also a component of the interleukin-13 receptor

Th2 cytokine signaling through IL-4Rα increases eotaxin-3 secretion and tension in human esophageal smooth muscle

In esophageal epithelial cells in eosinophilic esophagitis (EoE), Th2 cytokines (IL-4, IL-13) signal through IL-4Rα, activating JAK to increase eotaxin-3 secretion, which draws eosinophils into the mucosa. We explored whether Th2 cytokines also might stimulate eotaxin-3 secretion and increase tension in esophageal smooth muscle (ESM), which might impair esophageal distensibility, and whether those events could be blocked by proton pump inhibitors (PPIs) or agents that disrupt IL-4Rα signaling. We established human ESM cell cultures from organ donors, characterizing Th2 cytokine receptor and P-type ATPase expression by qPCR. We measured Th2 cytokine-stimulated eotaxin-3 secretion by enzyme-linked immunosorbent assay (ELISA) and ESM cell tension by gel contraction assay, before and after treatment with omeprazole, ruxolitinib (JAK inhibitor), or IL-4Rα blocking antibody. CPI-17 (inhibitor of a muscle-relaxing enzyme) effects were studied with CPI-17 knockdown by siRNA or CPI-17 phospho(T38A)-mutant overexpression. ESM cells expressed IL-4Rα and IL-13Rα1 but only minimal H+-K+-ATPase mRNA. Th2 cytokines increased ESM eotaxin-3 secretion and tension, effects blocked by ruxolitinib and IL-4Rα blocking antibody but not consistently blocked by omeprazole. IL-13 increased ESM tension by increasing CPI-17 expression and phosphorylation, effects blocked by CPI-17 knockdown. Blocking IL-4Rα decreased IL-13-stimulated eotaxin-3 secretion, CPI-17 expression, and tension in ESM. Th2 cytokines increase ESM eotaxin-3 secretion and tension via IL-4Rα signaling that activates CPI-17. Omeprazole does not reliably inhibit this process, but IL-4Rα blocking antibody does. This suggests that ESM eosinophilia and impaired esophageal distensibility might persist despite elimination of mucosal eosinophils by PPIs, and IL-4Rα blocking agents might be especially useful in this circumstance.NEW & NOTEWORTHY We have found that Th2 cytokines increase eotaxin-3 secretion and tension in esophageal smooth muscle (ESM) cells via IL-4Rα signaling. Unlike esophageal epithelial cells, ESM cells do not express H+-K+-ATPase, and omeprazole does not inhibit their cytokine-stimulated eotaxin-3 secretion or tension. An IL-4Rα blocking antibody reduces both eotaxin-3 secretion and tension induced by Th2 cytokines in ESM cells, suggesting that an agent such as dupilumab might be preferred for patients with EoE with esophageal muscle involvement.

Sensitization of colonic nociceptors by IL-13 is dependent on JAK and p38 MAPK activity

The effective management of visceral pain is a significant unmet clinical need for those affected by gastrointestinal diseases, such as inflammatory bowel disease (IBD). The rational design of novel analgesics requires a greater understanding of the mediators and mechanisms underpinning visceral pain. Interleukin-13 (IL-13) production by immune cells residing in the gut is elevated in IBD, and IL-13 appears to be important in the development of experimental colitis. Furthermore, receptors for IL-13 are expressed by neurons innervating the colon, though it is not known whether IL-13 plays any role in visceral nociception per se. To resolve this, we used Ca²⁺ imaging of cultured sensory neurons and ex vivo electrophysiological recording from the lumbar splanchnic nerve innervating the distal colon. Ca²⁺ imaging revealed the stimulation of small-diameter, capsaicin-sensitive sensory neurons by IL-13, indicating that IL-13 likely stimulates nociceptors. IL-13-evoked Ca²⁺ signals were attenuated by inhibition of Janus (JAK) and p38 kinases. In the lumbar splanchnic nerve, IL-13 did not elevate baseline firing, nor sensitize the response to capsaicin application, but did enhance the response to distention of the colon. In line with Ca²⁺ imaging experiments, IL-13-mediated sensitization of the afferent response to colon distention was blocked by inhibition of either JAK or p38 kinase signaling. Together, these data highlight a potential role for IL-13 in visceral nociception and implicate JAK and p38 kinases in pronociceptive signaling downstream of IL-13.

JAK-STAT signaling pathway in the pathogenesis of atopic dermatitis: An updated review

Atopic dermatitis (AD) is a chronic, inflammatory, pruritic form of dermatosis with heterogeneous manifestations that can substantially affect patients' quality of life. AD has a complex pathogenesis, making treatment challenging for dermatologists. The Janus kinase (JAK)-signal transducer and activator of transcription (STAT) pathway plays a central role in modulating multiple immune axes involved in the immunopathogenesis of AD. In particular, Th2 cytokines, including interleukin (IL)-4, IL-5, IL-13, IL-31, and thymic stromal lymphopoietin, which contribute to the symptoms of chronic inflammation and pruritus in AD, are mediated by JAK-STAT signal transduction. Furthermore, JAK-STAT is involved in the regulation of the epidermal barrier and the modulation of peripheral nerves related to the transduction of pruritus. Targeting the JAK-STAT pathway may attenuate these signals and show clinical efficacy through the suppression of various immune pathways associated with AD. Topical and oral JAK inhibitors with variable selectivity have emerged as promising therapeutic options for AD. Notably, topical ruxolitinib, oral upadacitinib, and oral abrocitinib were approved by the U.S. Food and Drug Administration for treating patients with AD. Accordingly, the present study reviewed the role of JAK-STAT pathways in the pathogenesis of AD and explored updated applications of JAK inhibitors in treating AD.

Exogenous IL-13 exacerbates Leishmania major infection and abrogates acquired immunity to re-infection

Cutaneous leishmaniasis is a major global health issue, affecting more than 88 countries with 0.7-1.2 million new cases per year. T helper polarization plays a significant role in disease outcome, with Th1 responses being associated with resistance and Th2 responses being associated with susceptibility. IL-13 is an important Th2 cytokine with structural and functional similarities to IL-4. In this study, we demonstrate that administering exogenous IL-13 to Leishmania major-infected BALB/c mice increases parasite load in the infected paw and decreases tissue levels of the key Th1/Th2 cytokines IFN-γ and IL-4, respectively. Infecting BALB/c mice with a low dose of L. major has previously been shown to confer resistance to re-infection with a higher dose. In this study, we demonstrate that administration of exogenous IL-13 early in the course of the initial low-dose infection abrogates acquired resistance to high-dose re-infection, as measured by infected paw thickness.

Significance of Interleukin (IL)-4 and IL-13 in Inflammatory Arthritis

Interleukin (IL)-4 and IL-13 belong to the T helper 2 (Th2) cytokine family, along with IL-3, IL-5, and IL-9. These cytokines are key mediators of allergic inflammation. They have important immunomodulatory activities and exert influence on a wide variety of immune cells, such as B cells, eosinophils, basophils, monocytes, fibroblasts, endothelial cells, airway epithelial cells, smooth muscle cells, and keratinocytes. Recent studies have implicated IL-4 and IL-13 in the development of various autoimmune diseases. Additionally, these cytokines have emerged as potential players in pathogenesis of inflammatory arthritis. Recent findings suggest that the IL-4 and IL-13 might play a significant role in the downregulation of inflammatory processes underlying RA pathology, and beneficially modulate the course of the disease. This review summarizes the biological features of the IL-4 and IL-13 and provides current knowledge regarding the role of these cytokines in inflammatory arthritis.

A key role for IL-13 signaling via the type 2 IL-4 receptor in experimental atopic dermatitis

IL-13 and IL-4 are potent mediators of type 2-associated inflammation such as those found in atopic dermatitis (AD). IL-4 shares overlapping biological functions with IL-13, a finding that is mainly explained by their ability to signal via the type 2 IL-4 receptor (R), which is composed of IL-4Rα in association with IL-13Rα1. Nonetheless, the role of the type 2 IL-4R in AD remains to be clearly defined. Induction of two distinct models of experimental AD in Il13ra1 ^-/- mice, which lack the type 2 IL-4R, revealed that dermatitis, including ear and epidermal thickening, was dependent on type 2 IL-4R signaling. Expression of TNF-α was dependent on the type 2 IL-4R, whereas induction of IL-4, IgE, CCL24, and skin eosinophilia was dependent on the type 1 IL-4R. Neutralization of IL-4, IL-13, and TNF-α as well as studies in bone marrow-chimeric mice revealed that dermatitis, TNF-α, CXCL1, and CCL11 expression were exclusively mediated by IL-13 signaling via the type 2 IL-4R expressed by nonhematopoietic cells. Conversely, induction of IL-4, CCL24, and eosinophilia was dependent on IL-4 signaling via the type 1 IL-4R expressed by hematopoietic cells. Last, we pharmacologically targeted IL-13Rα1 and established a proof of concept for therapeutic targeting of this pathway in AD. Our data provide mechanistic insight into the differential roles of IL-4, IL-13, and their receptor components in allergic skin and highlight type 2 IL-4R as a potential therapeutic target in AD and other allergic diseases such as asthma and eosinophilic esophagitis.

CXCR3A promotes the secretion of the antifibrotic decoy receptor sIL-13Rα2 by pulmonary fibroblasts

CXC chemokine receptor 3 (CXCR3) A and its IFN-inducible ligands CXCL9 and CXCL10 regulate vascular remodeling and fibroblast motility. IL-13 is a profibrotic cytokine implicated in the pathogenesis of inflammatory and fibroproliferative conditions. Previous work from our laboratory has shown that CXCR3A is negatively regulated by IL-13 and is necessary for the basal regulation of the IL-13 receptor subunit IL-13Rα2. This study investigates the regulation of fibroblast phenotype, function, and downstream IL-13 signaling by CXCR3A in vitro. CXCR3A was overexpressed via transient transfection. CXCR3A^-/- lung fibroblasts were isolated for functional analysis. Additionally, the contribution of CXCR3A to tissue remodeling following acute lung injury was assessed in vivo with wild-type (WT) and CXCR3^-/- mice challenged with IL-13. CXCR3 and IL-13Rα2 displayed a reciprocal relationship after stimulation with either IL-13 or CXCR3 ligands. CXCR3A reduced expression of fibroblast activation makers, soluble collagen production, and proliferation. CXCR3A enhanced the basal expression of pERK1/2 while inducing IL-13-mediated downregulation of NF-κB-p65. CXCR3A^-/- pulmonary fibroblasts were increasingly proliferative and displayed reduced contractility and α-smooth muscle actin expression. IL-13 challenge regulated expression of the CXCR3 ligands and soluble IL-13Rα2 levels in lungs and bronchoalveolar lavage fluid (BALF) of WT mice; this response was absent in CXCR3^-/- mice. Alveolar macrophage accumulation and expression of genes involved in lung remodeling was increased in CXCR3^-/- mice. We conclude that CXCR3A is a central antifibrotic factor in pulmonary fibroblasts, limiting fibroblast activation and reducing extracellular matrix (ECM) production. Therefore, targeting of CXCR3A may be a novel approach to regulating fibroblast activity in lung fibrosis and remodeling.

IL-4Rα expression by airway epithelium and smooth muscle accounts for nearly all airway hyperresponsiveness in murine allergic airway disease

Airway hyperresponsiveness (AHR) often defines asthma. Murine allergic airway disease (AAD), like human eosinophilic asthma, is characterized by AHR, eosinophilia, goblet cell metaplasia (GCM), smooth muscle hypercontractility, and increased production of IL-4 and IL-13-cytokines that induce these characteristics by binding to the IL-4Rα chain. We evaluated the epithelial and smooth muscle IL-4Rα-dependent contributions to AHR of BALB/c mice that possessed 0-2 functional IL-4Rα alleles and had airway disease induced by house dust mite extract (HDM) or exogenous IL-13. Two functional IL-4Rα alleles were required for maximal AHR, while only one functional allele was required for maximal GCM and systemic IL-4/IL-13 levels. Deletion of IL-4Rα from both smooth muscle and epithelial cells inhibited AHR >83% in mice with two functional IL-4Rα alleles. In mice with one functional IL-4Rα allele, selective epithelial cell IL-4Rα deletion maximally inhibited AHR, while selective smooth muscle IL-4Rα deletion decreased IL-13-induced, but not HDM-induced, AHR. Less IL-4Rα signaling is required to maximize the epithelial cell contribution to AHR compared to the smooth muscle contribution to AHR. In addition, epithelial cell responses to IL-4/IL-13 can increase the IL-4Rα-dependent smooth muscle contribution to AHR. These findings carry increasing relevance as IL-4Rα-targeted therapy is administered to human asthmatics.

Schistosome infection and its effect on pulmonary circulation

Schistosomiasis is the most common parasitic disease associated with pulmonary hypertension. It induces remodelling via complex inflammatory processes, which eventually produce the clinical manifestation of pulmonary hypertension. The pulmonary hypertension shows clinical signs and symptoms that are not distinguishable from other forms of pulmonary arterial hypertension.

Targeting IL-13 as a Host-Directed Therapy Against Ulcerative Colitis

The role of interleukin-13 in mediating ulcerative colitis remains under scrutiny. Compelling evidence from both man and mouse suggests that IL-13 not only contributes to the pathology associated with disease but is also involved in mediating the inflammatory response. These studies have led to the approach of targeting IL-13 as a promising treatment strategy in alleviating ulcerative colitis disease. Despite this evidence, recent clinical trial data suggests that specifically blocking the receptor through which IL-13 signals, IL-4 receptor-alpha (IL-4Rα) in ulcerative colitis patients, is insufficient in protecting them from disease outcome. This challenges the importance of IL-13 as a therapeutic target. This review describes the role of IL-13 in ulcerative colitis and current treatment strategies that target IL-13. The potential role of IL-13 signaling independently of IL-4Rα in mediating ulcerative colitis is highlighted as an important consideration when targeting the signaling mechanisms of IL-13 for therapeutic approaches.

Immunity to gastrointestinal nematode infections

Numerous species of nematodes have evolved to inhabit the gastrointestinal tract of animals and humans, with over a billion of the world's population infected with at least one species. These large multicellular pathogens present a considerable and complex challenge to the host immune system given that individuals are continually exposed to infective stages, as well as the high prevalence in endemic areas. This review summarizes our current understanding of host-parasite interactions, detailing induction of protective immunity, mechanisms of resistance, and resolution of the response. It is clear from studies of well-defined laboratory model systems that these responses are dominated by innate and adaptive type 2 cytokine responses, regulating cellular and soluble effectors that serve to disrupt the niche in which the parasites live by strengthening the physical mucosal barrier and ultimately promoting tissue repair.

A crucial role of the PD-1H coinhibitory receptor in suppressing experimental asthma

Programmed death one homolog (PD-1H) is a cell surface molecule of the B7/CD28 immune modulatory gene family. Although PD-1H has been shown to function as a coinhibitory receptor on T cells to limit naive T-cell activation and proliferation, its role in the regulation of the T-cell response to allergens is unknown. We report here that genetic ablation or blockade of PD-1H drastically promotes pulmonary inflammation with massive accumulation of eosinophils in a mouse model of experimental asthma, indicating a suppressive function of PD-1H in allergic inflammation. The loss of PD-1H led to elevated production of both innate cytokines (IL-6, MCP-1 and TNFα) and Th2 cytokines (IL-5 and IL-13) in the lung, indicating a critical role of PD-1H in suppressing the production of airway inflammatory cytokines. In addition, the loss of PD-1H also impaired the expansion of systemic and pulmonary regulatory T cells during asthma induction. These findings support a critical role of intrinsic PD-1H in the regulation of inflammatory responses to allergens. Finally, we showed that treatment with a PD-1H agonistic monoclonal antibody reduced the severity of asthma, which was accompanied by suppressed lung inflammation. Our findings support PD-1H as a potential target and suggest a possible strategy for the treatment of allergic asthma in humans.

Anrukinzumab, an anti-interleukin 13 monoclonal antibody, in active UC: efficacy and safety from a phase IIa randomised multicentre study

OBJECTIVE

Interleukin 13 (IL-13) is thought to play a key role as an effector cytokine in UC. Anrukinzumab, a humanised antibody that inhibits human IL-13, was evaluated for the treatment of UC.

DESIGN

In a multicentre, randomised, double-blind, placebo-controlled study, patients with active UC (Mayo score ≥4 and <10) were randomised to anrukinzumab 200, 400 or 600 mg or placebo. Patients received five intravenous administrations over 14 weeks. The primary endpoint was fold change from baseline in faecal calprotectin (FC) at Week 14. Secondary endpoints included safety, pharmacokinetics and IL-13 levels.

RESULTS

The modified intention-to-treat population included 84 patients (21 patients/arm). Fold change of FC from baseline at Week 14 was not significantly different for any treatment groups compared with the placebo. The study had a high dropout rate, in part, related to lack of efficacy. The exploratory comparisons of each dose were not significantly different from placebo in terms of change from baseline in total Mayo score, clinical response, clinical remission and proportion of subjects with mucosal healing. An increase in serum total IL-13 (free and bound to anrukinzumab) was observed for all anrukinzumab groups but not with placebo. This suggests significant binding of anrukinzumab to IL-13. The safety profile was not different between the anrukinzumab and placebo groups.

CONCLUSIONS

A statistically significant therapeutic effect of anrukinzumab could not be demonstrated in patients with active UC in spite of binding of anrukinzumab to IL-13.

TRIAL REGISTRATION NUMBER

ClinicalTrials.gov number NCT01284062.

Modulation of pulmonary fibrosis by IL-13Rα2

Pulmonary fibrosis is a progressive and fatal disease that involves the remodeling of the distal airspace and the lung parenchyma, which results in compromised gas exchange. The median survival time once diagnosed is less than three years. Interleukin (IL)-13 has been shown to play a role in a number of inflammatory and fibrotic diseases. IL-13 modulates its effector functions via a complex receptor system that includes the IL-4 receptor (R) α, IL-13Rα1, and the IL-13Rα2. IL-13Rα1 binds IL-13 with low affinity, yet, when it forms a complex with IL-4α, it binds with much higher affinity, inducing the effector functions of IL-13. IL-13Rα2 binds IL-13 with high affinity but has a short cytoplasmic tail and has been shown to act as a nonsignaling decoy receptor. Transfection of fibroblasts and epithelial cells with IL-13Rα2 inhibited the IL-13 induction of soluble collagen, TGF-β, and CCL17. Adenoviral overexpression of IL-13Rα2 in the lung reduced bleomycin-induced fibrosis. Our work shows that overexpression of IL-13Rα2 inhibits the IL-13 induction of fibrotic markers in vitro and inhibits bleomycin-induced pulmonary fibrosis. In summary our study highlights the antifibrotic nature of IL-13Ra2.

TH2 cells and their cytokines regulate formation and function of lymphatic vessels

Lymphatic vessels (LVs) are critical for immune surveillance and involved in the pathogenesis of diverse diseases. LV density is increased during inflammation; however, little is known about how the resolution of LVs is controlled in different inflammatory conditions. Here we show the negative effects of T helper type 2 (TH2) cells and their cytokines on LV formation. IL-4 and IL-13 downregulate essential transcription factors of lymphatic endothelial cells (LECs) and inhibit tube formation. Co-culture of LECs with TH2 cells also inhibits tube formation, but this effect is fully reversed by interleukin (IL)-4 and/or IL-13 neutralization. Furthermore, the in vivo blockade of IL-4 and/or IL-13 in an asthma model not only increases the density but also enhances the function of lung LVs. These results demonstrate an anti-lymphangiogenic function of TH2 cells and their cytokines, suggesting a potential usefulness of IL-4 and/or IL-13 antagonist as therapeutic agents for allergic asthma through expanding LV mediated-enhanced antigen clearance from the inflammatory sites.

Simulations of site-specific target-mediated pharmacokinetic models for guiding the development of bispecific antibodies

Bispecific antibodies (BAbs) are novel constructs that are under development and show promise as new therapeutic modalities for cancer and autoimmune disorders. The aim of this study is to develop a semi-mechanistic modeling approach to elucidate the disposition of BAbs in plasma and possible sites of action in humans. Here we present two case studies that showcase the use of modeling to guide BAb development. In case one, a BAb is directed against a soluble and a membrane-bound ligand for treating systemic lupus erythematosus, and in case two, a BAb targets two soluble ligands as a potential treatment for ulcerative colitis and asthma. Model simulations revealed important differences between plasma and tissues, when evaluated for drug disposition and target suppression. Target concentrations at tissue sites and type (soluble vs membrane-bound), tissue-site binding, and binding affinity are all major determinants of BAb disposition and subsequently target suppression. For the presented case studies, higher doses and/or frequent dosing regimens are required to achieve 80 % target suppression in site specific tissue (the more relevant matrix) as compared to plasma. Site-specific target-mediated models may serve to guide the selection of first-in-human doses for new BAbs.

IL-4 and IL-13 inhibit IL-1β and TNF-α induced kinin B1 and B2 receptors through a STAT6-dependent mechanism

BACKGROUND AND PURPOSE

Bone resorption induced by interleukin-1β (IL-1β) and tumour necrosis factor (TNF-α) is synergistically potentiated by kinins, partially due to enhanced kinin receptor expression. Inflammation-induced bone resorption can be impaired by IL-4 and IL-13. The aim was to investigate if expression of B1 and B2 kinin receptors can be affected by IL-4 and IL-13.

EXPERIMENTAL APPROACH

We examined effects in a human osteoblastic cell line (MG-63), primary human gingival fibroblasts and mouse bones by IL-4 and IL-13 on mRNA and protein expression of the B1 and B2 kinin receptors. We also examined the role of STAT6 by RNA interference and using Stat6(-/-) mice.

KEY RESULTS

IL-4 and IL-13 decreased the mRNA expression of B1 and B2 kinin receptors induced by either IL-1β or TNF-α in MG-63 cells, intact mouse calvarial bones or primary human gingival fibroblasts. The burst of intracellular calcium induced by either bradykinin (B2 agonist) or des-Arg(10) -Lys-bradykinin (B1 agonist) in gingival fibroblasts pretreated with IL-1β was impaired by IL-4. Similarly, the increased binding of B1 and B2 ligands induced by IL-1β was decreased by IL-4. In calvarial bones from Stat6-deficient mice, and in fibroblasts in which STAT6 was knocked down by siRNA, the effect of IL-4 was decreased.

CONCLUSIONS AND IMPLICATIONS

These data show, for the first time, that IL-4 and IL-13 decrease kinin receptors in a STAT6-dependent mechanism, which can be one important mechanism by which these cytokines exert their anti-inflammatory effects and impair bone resorption.

The potential for genetically altered microglia to influence glioma treatment

Diffuse and unstoppable infiltration of brain and spinal cord tissue by neoplastic glial cells is the single most important therapeutic problem posed by the common glioma group of tumors: astrocytoma, oligoastrocytoma, oligodendroglioma, their malignant variants and glioblastoma. These neoplasms account for more than two thirds of all malignant central nervous system tumors. However, most glioma research focuses on an examination of the tumor cells rather than on host-specific, tumor micro-environmental cells and factors. This can explain why existing diffuse glioma therapies fail and why these tumors have remained incurable. Thus, there is a great need for innovation. We describe a novel strategy for the development of a more effective treatment of diffuse glioma. Our approach centers on gaining control over the behavior of the microglia, the defense cells of the CNS, which are manipulated by malignant glioma and support its growth. Armoring microglia against the influences from glioma is one of our research goals. We further discuss how microglia precursors may be genetically enhanced to track down infiltrating glioma cells.

Due diligence in the characterization of matrix effects in a total IL-13 Singulex™ method

After obtaining her PhD in Cellular and Molecular biology from the University of Nevada, Reno, Stephanie has spent the last 15 years in the field of bioanalysis. She has held positions in academia, biotech, contract research and large pharma where she has managed ligand binding assay (discovery to Phase IIb clinical) and flow cytometry (preclinical) laboratories as well as taken the lead on implementing new/emergent technologies. Currently Stephanie leads Pfizer’s Regulated Bioanalysis Ligand Binding Assay group, focusing on early clinical biomarker support.

Interleukin (IL)-13, a Th2 cytokine, drives a range of physiological responses associated with the induction of allergic airway diseases and inflammatory bowel diseases. Analysis of IL-13 as a biomarker has provided insight into its role in disease mechanisms and progression. Serum IL-13 concentrations are often too low to be measured by standard enzyme-linked immunosorbent assay techniques, necessitating the implementation of a highly sensitive assay. Previously, the validation of a Singulex™ Erenna® assay for the quantitation of IL-13 was reported. Herein we describe refinement of this validation; defining the impact of matrix interference on the lower limit of quantification, adding spiked matrix QC samples, and extending endogenous IL-13 stability. A fit-for-purpose validation was conducted and the assay was used to support a Phase II clinical trial.

An IL-4/IL-13 dual antagonist reduces lung inflammation, airway hyperresponsiveness, and IgE production in mice

IL-4 and IL-13 comprise promising targets for therapeutic interventions in asthma and other Th2-associated diseases, but agents targeting either IL-4 or IL-13 alone have shown limited efficacy in human clinical studies. Because these cytokines may involve redundant function, dual targeting holds promise for achieving greater efficacy. We describe a bifunctional therapeutic targeting IL-4 and IL-13, developed by a combination of specific binding domains. IL-4-targeted and IL-13-targeted single chain variable fragments were joined in an optimal configuration, using appropriate linker regions on a novel protein scaffold. The bifunctional IL-4/IL-13 antagonist displayed high affinity for both cytokines. It was a potent and efficient neutralizer of both murine IL-4 and murine IL-13 bioactivity in cytokine-responsive Ba/F3 cells, and exhibited a half-life of approximately 4.7 days in mice. In a murine model of ovalbumin-induced ear swelling, the bifunctional molecule blocked both the IL-4/IL-13-dependent early-phase response and the IL-4-dependent late-phase response. In the ovalbumin-induced lung inflammation model, the bifunctional IL-4/IL-13 antagonist reduced the IL-4-dependent rise in serum IgE titers, and reduced IL-13-dependent airway hyperresponsiveness, lung inflammation, mucin gene expression, and serum chitinase responses. Taken together, these findings demonstrate the effective dual blockade of IL-4 and IL-13 with a single agent, which resulted in the modulation of a more extensive range of endpoints than could be achieved by targeting either cytokine alone.

Single nucleotide polymorphism in the promoter of the human interleukin-13 gene is associated with asthma in Malaysian adults

Asthma susceptibility genes are mapped to a region on human chromosome 5q31-q33, which contains a cluster of proinflammatory cytokine genes such as interleukin-13 (IL-13), which is associated with asthma. This study investigated the allele frequencies of two single nucleotide polymorphisms (SNPs) (−1111C>T and 4257C>A) in the IL-13 gene between asthmatics and healthy volunteers as well as the relationship between these SNPs and IL-13 production. DNA extracted from buffy coat of asthmatic and control subjects was genotyped using the PCR-RFLP method. Amount of IL-13 produced by mitogen-stimulated peripheral blood leucocytes PBLs (PBLs) was determined by ELISA. The frequencies of the −1111C and 4257G wild-type alleles were 0.52 and 0.55 in asthmatics and were 0.67 and 0.56 in controls. A significant (P < 0.05) association was found between genotype and allele frequencies of SNP at position −1111C>T between asthmatic and control groups (OR, 1.810; 95% CI = 1.184 to 2.767; P < 0.05). The mitogen-stimulated PBLs from asthmatics produced higher amounts of IL-13 production (P < 0.001). The 4257GA heterozygous and 4257AA homozygous mutant alleles were associated with higher IL-13 production in asthmatics (P < 0.05). Our results show that the −1111T mutant allele are associated with asthma and the 4257A mutant alleles are associated with elevated IL-13 production.

IL-4Rα on CD4+ T cells plays a pathogenic role in respiratory syncytial virus reinfection in mice infected initially as neonates

RSV is the major cause of severe bronchiolitis in infants, and severe bronchiolitis as a result of RSV is associated with subsequent asthma development. A biased Th2 immune response is thought to be responsible for neonatal RSV pathogenesis; however, molecular mechanisms remain elusive. Our data demonstrate, for the first time, that IL-4Rα is up-regulated in vitro on human CD4(+) T cells from cord blood following RSV stimulation and in vivo on mouse pulmonary CD4(+) T cells upon reinfection of mice, initially infected as neonates. Th cell-specific deletion of Il4ra attenuated Th2 responses and abolished the immunopathophysiology upon reinfection, including airway hyper-reactivity, eosinophilia, and mucus hyperproduction in mice infected initially as neonates. These findings support a pathogenic role for IL-4Rα on Th cells following RSV reinfection of mice initially infected as neonates; more importantly, our data from human cells suggest that the same mechanism occurs in humans.

Inhibitory effects of recombinant IL-4 and recombinant IL-13 on UHMWPE-induced bone destruction in the murine air pouch model

PURPOSE

We administered recombinant interleukin (IL)-4 and recombinant IL-13 locally into the air pouch of mice to improve bone resorption induced by ultra-high-molecular-weight polyethylene (UHMWPE) particles.

METHODS

Air pouches were established on the back of BALB/c mice, followed by the surgical introduction of a section of calvaria from a syngeneic mouse donor. We stimulated the bone-implanted pouches with the UHMWPE suspension. We divided UHMWPE-containing mice into four study groups to receive injections of phosphate-buffered saline (control), IL-4 alone, IL-13 alone, or IL-4 and IL-13 into the pouches. We harvested the tissues at 14 d after treatment for molecular and histological analyses.

RESULTS

The inhibitory effect of IL-4 was stronger than that of IL-13 toward osteoclast differentiation and osteoblast for the induction of osteoprotegerin production and down-regulation of receptor for activation of nuclear factor-κB ligand production. Furthermore, the combined treatment with both IL-4 and 1L-13 had a more important role in inhibiting bone resorption in these pouches with UHMWPE stimulation, compared with IL-4 or IL-13 treatment alone.

CONCLUSIONS

Local administration of recombinant IL-4 and IL-13 may be a feasible and effective therapeutic candidate to treat or prevent wear debris-associated osteolysis.

Long-lasting immune responses 4 years after GAD-alum treatment in children with type 1 diabetes

A phase II clinical trial with glutamic acid decarboxylase (GAD) 65 formulated with aluminium hydroxide (GAD-alum) has shown efficacy in preserving residual insulin secretion in children and adolescents with recent-onset type 1 diabetes (T1D). We have performed a 4-year follow-up study of 59 of the original 70 patients to investigate long-term cellular and humoral immune responses after GAD-alum-treatment. Peripheral blood mononuclear cells (PBMC) were stimulated in vitro with GAD₆₅. Frequencies of naïve, central and effector memory CD4+ and CD8+ T cells were measured, together with cytokine secretion, proliferation, gene expression and serum GAD₆₅ autoantibody (GADA) levels. We here show that GAD-alum-treated patients display increased memory T-cell frequencies and prompt T-cell activation upon in vitro stimulation with GAD₆₅, but not with control antigens, compared with placebo subjects. GAD₆₅-induced T-cell activation was accompanied by secretion of T helper (Th) 1, Th2 and T regulatory cytokines and by induction of T-cell inhibitory pathways. Moreover, post-treatment serum GADA titres remained persistently increased in the GAD-alum arm, but did not inhibit GAD₆₅ enzymatic activity. In conclusion, memory T- and B-cell responses persist 4 years after GAD-alum-treatment. In parallel to a GAD₆₅-induced T-cell activation, our results show induction of T-cell inhibitory pathways important for regulating the GAD₆₅ immunity.

IL-13 induces connective tissue growth factor in rat hepatic stellate cells via TGF-β-independent Smad signaling

Connective tissue growth factor (CTGF) plays a central role in stimulating extracellular matrix deposition in the liver, and hence is considered a critical mediator of TGF-β-dependent fibrogenesis. Hepatic stellate cells (HSCs) are known as the major source of CTGF in damaged liver. However, previous studies revealed that IL-13, rather than TGF-β, represents the predominant inducer of CTGF expression in HSCs. We now dissected IL-13 downstream signaling that modulates CTGF expression in HSCs. IL-13 induces a time- and dosage-dependent increase of CTGF in a TGF-β-independent manner. This process requires participation of different Smad proteins and their upstream receptor kinases (activin receptor-like kinases). Smad1 and Smad2 were identified as the key mediators of IL-13-dependent CTGF expression. Furthermore, IL-13 induces Stat6 phosphorylation in HSCs, but Stat6 was not involved in CTGF induction. Instead, the Erk1/2-MAPK pathway was found to be responsible for IL-13-induced early Smad phosphorylation and CTGF synthesis. We demonstrate that IL-13 induces CTGF expression in HSCs by activating TGF-β-independent activin receptor-like kinase/Smad signaling via the Erk-MAPK pathway rather than via its canonical JAK/Stat6 pathway. These results provide an improved new insight into the molecular mechanisms of profibrotic IL-13 activities in the liver.

The genetic impact of the Q551R interleukin-4 receptor alpha polymorphism for aggressive or chronic periodontitis and the occurrence of periodontopathic bacteria

OBJECTIVE

The Q551R polymorphism of the gene encoded for the α chain of the interleukin-4 receptor (IL-4RA) could influence both IL-4 and IL-13 signalling. Since both cytokines could be important in the pathogenesis of periodontitis the aim of this study was to evaluate putative associations of the Q551R polymorphism to generalized aggressive or chronic periodontitis and five periodontopathogens.

DESIGN

154 patients with severe generalized periodontitis (chronic: n=68, mean age=48.7 ± 9.4 years; aggressive: n=86, mean age=40.4 ± 9.8 years) and controls without periodontitis (n=89, mean age=46.2 ± 10.8 years) were included. The Q551R polymorphism was analysed by PCR-SSP CTS-Kit, Heidelberg, Germany. Subgingival bacteria were determined molecular biologically using micro-Ident test (HainLifescience, Nehren, Germany). Distributions of single alleles and genotypes were calculated by Chi(2)-test with Yates correction or Fisher's exact test. Adjusted odds ratios were generated by logistic regression with respect to established cofactors for periodontitis.

RESULTS

The mutant allele R551 (p(Y)=0.013) and the genotypes QR+RR (p(B)=0.024) occurred more frequently amongst patients with chronic periodontitis vs. controls. Carriers of the Q551R polymorphism had an increased adjusted odds ratio for chronic periodontitis (OR=3.2, 95%CI 1.5-6.5, p=0.002) and severe periodontitis (chronic+aggressive) in general (OR=2.0, 95%CI 1.1-3.6, p=0.003). Moreover, in the total study cohort the Q551R polymorphism was associated with the presence of Tannerella forsythia (90.3% vs. 78.0%, p(Y)=0.01).

CONCLUSIONS

The Q551R IL-4RA polymorphism is a putative risk indicator for severe chronic periodontitis, but was not significant associated to AP.

Role of macrophage migration inhibitory factor in the Th2 immune response to epicutaneous sensitization

We examined the role of macrophage migration inhibitory factor (MIF) in the generation of the Th2 response using MIF-deficient mice in a model of epicutaneous sensitization to ovalbumin. Lymph node cells from sensitized MIF-deficient mice produce lower levels of Th2 cytokines after antigen challenge when compared to their wild-type counterparts. Sensitized mice lacking MIF show less pulmonary inflammation after intranasal antigen exposure. Mice deficient in CD74, the MIF receptor, also are unable to generate an inflammatory response to epicutaneous sensitization. Examination of the elicitation phase of the atopic response using DO11.10 OVA TCR transgenic animals shows that T cell proliferation and IL-2 production are strongly impaired in MIF-deficient T cells. This defect is most profound when both T cells and antigen-presenting cells are lacking MIF. These data suggest that MIF is crucial both for the sensitization and the elicitation phases of a Th2-type immune response in allergic disease.

Interleukin-13 (IL-13)/IL-13 receptor alpha1 (IL-13Ralpha1) signaling regulates intestinal epithelial cystic fibrosis transmembrane conductance regulator channel-dependent Cl- secretion

Interleukin-13 (IL-13) has been linked to the pathogenesis of inflammatory diseases of the gastrointestinal tract. It is postulated that IL-13 drives inflammatory lesions through the modulation of both hematopoietic and nonhematopoietic cell function in the intestine. To delineate the relevant contribution of elevated levels of intestinal IL-13 to intestinal structure and function, we generated an intestinal IL-13 transgenic mouse (iIL-13Tg). We show that constitutive overexpression of IL-13 in the small bowel induces modification of intestinal epithelial architecture (villus blunting, goblet cell hyperplasia, and increased epithelial proliferation) and epithelial function (altered basolateral → apical Cl(-) ion conductance). Pharmacological analyses in vitro and in vivo determined that elevated Cl(-) conductance is mediated by altered cystic fibrosis transmembrane conductance regulator expression and activity. Generation of iIL-13Tg/Il13rα1(-/-), iIL-13Tg/Il13rα2(-/-), and iIL-13Tg/Stat6(-/-) mice revealed that IL-13-mediated dysregulation of epithelial architecture and Cl(-) conductance is dependent on IL-13Rα1 and STAT-6. These observations demonstrate a central role for the IL-13/IL-13Rα1 pathway in the regulation of intestinal epithelial cell Cl(-) secretion via up-regulation of cystic fibrosis transmembrane conductance regulator, suggesting an important role for this pathway in secretory diarrhea.

αMβ₂ integrin activation prevents alternative activation of human and murine macrophages and impedes foam cell formation

RATIONALE

The alternative activation of monocytes by interleukin (IL)-13 and IL-4 is a significant component of the inflammatory response. The consequences of alternative activation in inflammatory diseases remain to be determined.

OBJECTIVE

In this report, we explored how integrins, receptors important for monocyte migration to inflammatory sites, regulate IL-13-mediated monocyte activation. We focused on the analysis of 2 proteins, which are upregulated during the alternative activation and are important for the development of atherosclerosis, an oxidative enzyme 15-lipoxygenase (15-LO) and a scavenger receptor CD36.

METHODS AND RESULTS

We found that adhesion of resting monocytes through β(2) integrins and inside-out activation of β(2) integrins by monocyte chemoattractant protein-1 did not change IL-13-stimulated 15-LO upregulation; however, preincubation of monocytes with the antibody MEM48, which generates full activation of β(2) integrins, significantly inhibited 15-LO mRNA and protein expression. In contrast, activation of β(1) integrins had no effect on 15-LO expression. Analysis of integrin clustering through α(M), α(L), α(X), and α(D) subunits demonstrated the pivotal role for integrin α(M)β(2) in inhibiting 15-LO expression. IL-13 treatment upregulates 15-LO-dependent CD36 expression on human monocytes; our studies showed that β(2) integrin activation and α(M) integrin clustering significantly inhibited IL-13-dependent CD36 mRNA and protein expression, as well as CD36-related foam cell formation. Moreover, IL-13 stimulation of α(M)-deficient peritoneal macrophages demonstrated an upregulated level of 15-LO induction, CD36 expression, and lipid accumulation as compared with wild-type controls.

CONCLUSIONS

The adhesion of monocytes/macrophages through activated integrin α(M)β(2) has a regulatory and potential atheroprotective function during the alternative activation of macrophages.

PIBF: the double edged sword. Pregnancy and tumor

PROBLEM

The role of progesterone-dependent immunomodulation in the maintenance of normal pregnancy.

METHODS

In vitro and in vivo data on the effect that progesterone and its mediator progesterone-induced blocking factor (PIBF) exert on the immune functions of pregnant women are reviewed, together with clinical findings.

RESULTS

Activated pregnancy lymphocytes express progesterone receptors, which enable progesterone to induce a protein called PIBF. PIBF increases Th2 type cytokine production by signaling via a novel type of IL-4 receptor and activating the Jak/STAT pathway. PIBF inhibits phosholipase A2, thus reduces prostaglandin synthesis. PIBF inhibits perforin release in human decidual lymphocytes and reduces the deleterious effect of high NK activity on murine pregnancy. PIBF production is a characteristic feature of normal human pregnancy, and its concentration is reduced in threatened pregnancies. PIBF mRNA and protein are expressed in a variety of malignant tumors. Inhibition of PIBF synthesis increases survival rates of leukemic mice.

CONCLUSION

Progesterone-induced blocking factor is produced by pregnancy lymphocytes and also by malignant tumors. The PIBF-induced Th2-dominant immune response is favorable during pregnancy but might facilitate tumor growth by suppressing local antitumor immune responses.

IL-13 receptor alpha2 regulates the immune and functional response to Nippostrongylus brasiliensis infection

IL-13 has a prominent role in host defense against the gastrointestinal nematode Nippostrongylus brasiliensis; however, the role of IL-13Ralpha2 in the immune and functional response to enteric infection is not known. In the current study, we investigated changes in smooth muscle and epithelial cell function as well as alterations in gene expression of IL-13 and IL-4 and their receptors using laser-capture microdissection of specific cell types in the small intestine of N. brasiliensis-infected mice. An infection-induced up-regulation of IL-13Ralpha2 gene expression was confined to smooth muscle and was dependent on STAT6 and IL-13, but not on IL-4. In contrast, expression of IL-13Ralpha1 was reduced, indicating that changes in IL-13alpha2 expression serve to limit the biological effects of IL-13. The increased availability of IL-13 in IL-13Ralpha2(-/-) mice resulted in marked changes in constitutive epithelial and smooth muscle function. In addition, maximal changes in smooth muscle hypercontractility and epithelial cell resistance peaked earlier after infection in IL-13Ralpha2(-/-) compared with wild-type mice. This did not coincide with an earlier Th2 immune response as expression of IL-4 and IL-13 was attenuated in IL-13Ralpha2(-/-) mice and worm expulsion was similar to that of wild-type mice. These data show that IL-13Ralpha2 plays an important role in nematode infection by limiting the availability of IL-13 during infection, thereby regulating both the immune and biological effects of IL-13.

Sho-seiryu-to suppresses histamine signaling at the transcriptional level in TDI-sensitized nasal allergy model rats

BACKGROUND

The therapeutic use of Kampo medicine, Sho-seiryu-to (SST) in allergic disorders is well known. As histamine plays a central role in allergic diseases, it is possible that SST affects the allergy-related histamine signaling. In this study, we investigated the effect of SST on allergy-related histamine signaling in the nasal mucosa of toluene 2, 4-diisocyanate (TDI)-sensitized nasal allergy model rats.

METHODS

Six-week-old male, Brown Norway rats were sensitized for 2 weeks with 10 microl of 10% TDI, and after a 1 week interval, provocation was initiated with the same amount of TDI. SST (0.6g/rat) was given orally 1 hour before TDI treatment began for a period of 3 weeks. Nasal symptoms were scored for 10 minutes immediately after TDI-provocation. The genes expression in nasal mucosa was determined using real-time quantitative RT-PCR.

RESULTS

SST significantly suppressed TDI-induced nasal allergy-like symptoms. TDI provocation showed a significant up-regulation of histamine H(1) receptor (H1R) and histidine decarboxylase (HDC) gene expressions. Prolonged pre-treatment of SST significantly suppressed the mRNA levels of H1R and HDC that was up-regulated by TDI. SST also suppressed TDI-induced interleukin (IL)-4 and IL-5 mRNA elevation. However, SST showed no significant effect for TDI-induced mRNA elevation of IL-13.

CONCLUSIONS

These results demonstrate that SST alleviates nasal symptoms by the inhibition of histamine signaling through suppression of TDI-induced H1R and HDC gene up-regulation. SST also suppresses cytokine signaling through suppression of IL-4 and IL-5 gene expression. Suppression of histamine signaling may be a novel mechanism of SST in preventing allergic diseases.

Lysophosphatidic acid signaling in airway epithelium: role in airway inflammation and remodeling

Lysophosphatidic acid (LPA), a potent bioactive phospholipid, induces diverse cellular responses, including cell proliferation, migration, and cytokine release. LPA can be generated intracellularly and extracellularly through multiple synthetic pathways by action of various enzymes, such as phospholipase A(1/2) (PLA(1/2)), phospholipase D (PLD), acylglycerol kinase (AGK), and lysophospholipase D (lysoPLD). Metabolism of LPA is regulated by a family of lipid phosphate phosphatases (LPPs). Significant amounts of LPA have been detected in various biological fluids, including serum, saliva, and bronchoalveolar lavage fluid (BALF). The most significant effects of LPA appear to be through activation of the G-protein-coupled receptors (GPCRs), termed LPA(1-6). LPA regulates gene expression through activation of several transcriptional factors, such as nuclear factor-kappaB (NF-kappaB), AP-1, and C/EBPbeta. In addition to GPCRs, cross-talk between LPA receptors and receptor tyrosine kinases (RTKs) partly regulates LPA-induced intracellular signaling and cellular responses. Airway epithelial cells participate in innate immunity through the release of cytokines, chemokines, lipid mediators, other inflammatory mediators and an increase in barrier function in response to a variety of inhaled stimuli. Expression of LPA receptors has been demonstrated in airway epithelial cells. This review summarizes our recent observations of the role of LPA/LPA-Rs in regulation of airway epithelium, especially in relation to the secretion of pro- and anti-inflammatory mediators and regulation of airway barrier function.

IL-13 cytotoxin has potent antitumor activity and synergizes with paclitaxel in a mouse model of oral squamous cell carcinoma

Interleukin-13 receptor-targeted cytotoxin (IL13-PE38) is highly cytotoxic to certain types of human cancers expressing abundant levels of IL-13Ralpha2 chain. Although IL13-PE38 is being tested in a Phase III clinical trial in brain tumors, the activity of IL13-PE38 alone or when combined with taxane, a chemotherapeutic drug for oral squamous cell carcinoma (OSCC), has not been investigated. Here, we show that approximately 40% of OSCCs (n = 50) in a tissue array are strongly positive for IL-13Ralpha2, whereas normal oral mucosa (n = 10) expresses very low or undetectable levels evaluated by immunohistochemistry. IL13-PE38 was highly cytotoxic to OSCC cell lines, but not cytotoxic to normal oral fibroblasts. IL13-PE38 mediated a synergistic antitumor effect with paclitaxel in OSC-19 in vitro and in vivo in the orthotopic OSCC tongue tumor model. Real-time tumor growth was monitored by optical imaging using a Xenogen-IVIS imaging system. Treated animals showed significant (p < 0.05) improvement in survival, which correlated with in vivo imaging of tumor response without evidence of visible toxicity. Gene transfer of IL-13Ralpha2 in oral cancer cells increased sensitivity of OSCC cell line to IL13-PE38 in vitro. Retrovirus-mediated gene-transfer of IL-13Ralpha2 in HSC-3 into tongue tumors in vivo dramatically enhanced the antitumor activity of IL13-PE38, providing complete elimination of established tumors and prolonging survival of these animals. These results indicate that IL13-PE38 in combination with paclitaxel acting via different mechanisms may be a potential treatment option for IL-13Ralpha2 expressing OSCC or for the treatment of non-IL-13Ralpha2 expressing OSCC combined with gene transfer of IL-13Ralpha2.

Genes and structure of selected cytokines involved in pathogenesis of psoriasis

Psoriasis is a common skin disease involving 1-4% of human population worldwide, of strong genetic background. The following cytokines are directly involved in psoriasis: TNF, IL-1, IL-2, IL-6, IL-7, IL-8, IL-15, IL-18, IL-19, IL-20, IL-23 whereas IL-4, IL-10, IL-12 as well as IL-11, IL-17 and IFN-gamma are rather indirectly engaged. This work is a review of some genetic factors and structure of selected cytokines and receptors and their genes location.

Binding characterization of the interleukin-13 signaling complex and development of a ternary time-resolved fluorescence resonance energy transfer assay

Interleukin-13 (IL-13) is a critical mediator of pulmonary pathology associated with asthma. Drugs that block the biological function of IL-13 may be an effective treatment for asthma. IL-13 signals by forming a ternary complex with IL-13Ralpha1 and IL-4R. Genetic variants of IL-13 and of its receptor components have been linked to asthma. One in particular, IL-13R110Q, is associated with increased IgE levels and asthma. We characterized the interactions of the binary complexes composed of IL-13 or IL-13R110Q with IL-13Ralpha1 and the ternary complexes composed of IL-13 or IL-13R110Q and IL-13Ralpha1 with IL-4R using surface plasmon resonance and time-resolved fluorescence resonance energy transfer (TR-FRET). By both biophysical methods, we found no differences between IL-13 and IL-13R110Q binding in either the binary or the ternary complex. IL-4R bound to the IL-13/IL-13Ralpha1 complex with slow on and off rates, resulting in a relatively weak affinity of about 100nM. We developed a TR-FRET assay targeting the interaction between the IL-4R and the binary complex. Two antibodies with known binding epitopes to IL-13 that block binding to either IL-13Ralpha1 or IL-4R inhibited the TR-FRET signal formed by the ternary complex. This assay will be useful to identify and characterize inhibitory molecules of IL-13 function.

Differences in expression, affinity, and function of soluble (s)IL-4Ralpha and sIL-13Ralpha2 suggest opposite effects on allergic responses

IL-4 and IL-13 are each bound by soluble receptors (sRs) that block their activity. Both of these sRs (sIL-4Ralpha and sIL-13Ralpha2) are present in low nanogram per milliliter concentrations in the serum from unstimulated mice, but differences in affinity and half-life suggest differences in function. Serum IL-4/sIL-4Ralpha complexes rapidly dissociate, releasing active IL-4, whereas sIL-13Ralpha2 and IL-13 form a stable complex that has a considerably longer half-life than uncomplexed IL-13, sIL-13Ralpha2, IL-4, or sIL-4Ralpha. Approximately 25% of sIL-13Ralpha2 in serum is complexed to IL-13; this percentage and the absolute quantity of sIL-13Ralpha2 in serum increase considerably during a Th2 response. sIL-13Ralpha2 gene expression is up-regulated by both IL-4 and IL-13; the effect of IL-4 is totally IL-4Ralpha-dependent while the effect of IL-13 is partially IL-4Ralpha-independent. Inhalation of an IL-13/sIL-13Ralpha2 complex does not affect the expression of IL-13-inducible genes but increases the expression of two genes, Vnn1 and Pira-1, whose products activate APCs and promote neutrophilic inflammation. These observations suggest that sIL-4Ralpha predominantly sustains, increases, and diffuses the effects of IL-4, whereas sIL-13Ralpha2 limits the direct effects of IL-13 to the site of IL-13 production and forms a stable complex with IL-13 that may modify the quality and intensity of an allergic inflammatory response.

TLR9 activation is a key event for the maintenance of a mycobacterial antigen-elicited pulmonary granulomatous response

Type 1 (Th1) granulomas can be studied in mice sensitized with mycobacterium antigens followed by challenge of agarose beads covalently coupled to purified protein derivative. TLR9 is known to play a role in the regulation of Th1 responses; thus, we investigated the role of TLR9 in granuloma formation during challenge with mycobacterium antigens and demonstrated that mice deficient in TLR9 had increased granuloma formation, but a dramatically altered cytokine phenotype. Th1 cytokine levels of IFN-gamma and IL-12 in the lungs were decreased in TLR9(-/-) mice when compared to wild-type mice. In contrast, Th2 cytokine levels of IL-4, IL-5, and IL-13 were increased in TLR9(-/-) mice. The migration of CD4(+) T cells in the granuloma was impaired, while the number of F4/80(+) macrophages was increased in TLR9(-/-) mice. Macrophages in the lungs of the TLR9-deficient animals with developing granulomas expressed significantly lower levels of the classically activated macrophage marker, nitric oxide synthase, but higher levels of the alternatively activated macrophage markers such as 'found in inflammatory zone-1' antigen and Arginase-1. These results suggest that TLR9 plays an important role in maintaining the appropriate phenotype in a Th1 granulomatous response.

Murine IL-4 is able to signal via chimeric human IL-4Ralpha/mouse gamma-chain receptor

Human IL-4Ralpha binds to mouse gammac resulting in a chimeric receptor specific for human IL-4 but not mouse IL-4, providing in principle an inducible hIL-4 system. We investigated the in vitro and in vivo characteristics of human IL-4Ralpha transgenic mice on a mouse IL-4Ralpha-deficient background (hIL-4Ralpha Tg/mIL-4Ralpha(-/-)). The integrity of lymphocyte-specific hIL-4Ralpha expression in hIL-4Ralpha Tg/mIL-4Ralpha(-/-) mice was demonstrated by FACS analysis. This was confirmed in functional studies as lymphocytes responded to recombinant hIL-4 but not mIL-4 or mIL-13 in proliferation and T helper differentiation assays, demonstrating species-specificity and inducibility of the chimeric receptor in vitro. We then infected transgenic mice with Nippostrongylus brasiliensis, known to induce a strong Type 2 response in wild-type mice. As expected hIL-4Ralpha Tg/mIL-4Ralpha(-/-) mice were unable to expel N. brasiliensis worms which confirms unresponsiveness in non-lymphocytes. However they developed a Th2 cytokine and IgE response in the absence of induction with hIL-4. These results suggested that lymphocyte-specific IL-4Ralpha responsiveness was still present in vivo. Neutralization of endogenous mIL-4 resulted in inhibition of N. brasiliensis-induced Th2 cytokine and total IgE production in hIL-4Ralpha Tg/mIL-4Ralpha(-/-) mice suggesting that mIL-4 was involved. Intercrossing hIL-4Ralpha Tg/mIL-4Ralpha(-/-) mice with mIL-4(-/-)/mIL-13(-/-) mice completely abrogated Type 2 responses in N. brasiliensis infections. Together, these data demonstrate that mIL-4 triggered the hIL-4Ralpha/mgammac chimeric receptor in vivo.

IL-13 is pivotal in the fibro-obliterative process of bronchiolitis obliterans syndrome

Acute allograft rejection is considered to be a predominately type 1 immune mediated response to the donor alloantigen. However, the type 2 immune mediated response has been implicated in multiple fibroproliferative diseases. Based on the fibro-obliterative lesion found during bronchiolitis obliterans syndrome (BOS), we hypothesized that the type 2 immune mediated response is involved in chronic lung allograft rejection. Specifically, whereas acute rejection is, in part, a type 1 immune response, chronic rejection is, in part, a type 2 immune response. We found the type 2 cytokine, IL-13, to be elevated and biologically active in human bronchoalveolar lavage fluid during BOS. Translational studies using a murine model of BOS demonstrated increased expression of IL-13 and its receptors that paralleled fibro-obliteration. In addition, in vivo neutralization of IL-13 reduced airway allograft matrix deposition and murine BOS, by a mechanism that was independent of IL-4. Furthermore, using IL-13Ralpha2(-/-) mice, we found increased fibro-obliteration. Moreover, anti-IL-13 therapy in combination with cyclosporin A had profound effects on reducing murine BOS. This supports the notion that IL-13 biological axis plays an important role during the pathogenesis of BOS independent of the IL-4 biological axis.

Lysophosphatidic acid induces interleukin-13 (IL-13) receptor alpha2 expression and inhibits IL-13 signaling in primary human bronchial epithelial cells

Interleukin-13 (IL-13), a Th2 cytokine, plays a pivotal role in pathogenesis of bronchial asthma via IL-13 receptor alpha1 (IL-13Ralpha1) and IL-4 receptor alpha (IL-4Ralpha). Recent studies show that a decoy receptor for IL-13, namely IL-13Ralpha2, mitigates IL-13 signaling and function. This study provides evidence for regulation of IL-13Ralpha2 production and release and IL-13-dependent signaling by lysophosphatidic acid (LPA) in primary cultures of human bronchial epithelial cells (HBEpCs). LPA treatment of HBEpCs in at imedependent fashion increased IL-13Ralpha2 gene expression without altering the mRNA levels of IL-13Ralpha1 and IL-4Ralpha. Pretreatment with pertussis toxin (100 ng/ml, 4 h) or transfection of c-Jun small interference RNA or an inhibitor of JNK attenuated LPA-induced IL-13Ralpha2 gene expression and secretion of soluble IL-13Ralpha2. Overexpression of catalytically inactive mutants of phospholipase D (PLD) 1 or 2 attenuated LPA-induced IL-13Ralpha2 gene expression and protein secretion as well as phosphorylation of JNK. Pretreatment of HBEpCs with 1 microM LPA for 6 h attenuated IL-13-but not IL-4-induced phosphorylation of STAT6. Transfection of HBEpCs with IL-13Ralpha2 small interference RNA blocked the effect of LPA on IL-13-induced phosphorylation of STAT6. Furthermore, pretreatment with LPA (1 microM, 6 h) attenuated IL-13-induced eotaxin-1 and SOCS-1 gene expression. These results demonstrate that LPA induces IL-13Ralpha2 expression and release via PLD and JNK/AP-1 signal transduction and that pretreatment with LPA down-regulates IL-13 signaling in HBEpCs. Our data suggest a novel mechanism of regulation of IL-13Ralpha2 and IL-13 signaling that may be of physiological relevance to airway inflammation and remodeling.

Role of interleukin-13 in cancer, pulmonary fibrosis, and other T(H)2-type diseases

Interleukin (IL)-13 plays a major role in various inflammatory diseases including cancer, asthma, and allergy. It mediates a variety of different effects on various cell types including B cells, monocytes, natural killer cells, endothelial cells, and fibroblasts. IL-13 binds to two primary receptor chains IL-13Ralpha1 and IL-13Ralpha2. The IL-13Ralpha2 but not IL-13Ralpha1 chain binds IL-13 with high affinity and is overexpressed in a variety of human cancer cells derived from glioma, squamous cell carcinoma of head and neck, and AIDS-associated Kaposi's sarcoma. We have also demonstrated that IL-13Ralpha2 expression is greatly increased in lung cells when mice were challenged intranasally with bleomycin or Aspergillus fumigatus. In addition, IL-13Ralpha2 increased in surgical lung biopsies from patients with usual interstitial pneumonia, nonspecific interstitial pneumonia, and respiratory bronchiolitic interstitial pneumonia of unknown origin. Based on various studies, it is concluded that IL-13Ralpha2-expressing cells are involved in various pulmonary pathological conditions. In contrast, normal tissues such as brain, lung, endothelial cells, and head and neck tissues express IL-13Ralpha1 chain, but show only marginal expression of IL-13Ralpha2 chain. Thus, IL-13Ralpha2 chain may serve as a novel biomarker for diseased cells such as cancer or fibrosis and a target for receptor-directed therapeutic agents. To target IL-13R, a recombinant fusion protein composed of IL-13 and a derivative of Pseudomonas exotoxin (PE) has been produced. This cytotoxin termed as IL-13PE38QQR or IL-13PE38, or IL-13PE is highly and specifically cytotoxic to a variety of human tumor cell lines. In preclinical models of human glioblastoma, head and neck and AIDS-associated Kaposi's cancer, IL-13PE has been found to have significant antitumor activity at a tolerated dose. Several phase I clinical trials have been completed in patients with recurrent malignant glioma. Recently a phase III clinical trial (PRECISE) in patients with recurrent malignant glioma has been completed recruiting a total of 294 patients. IL-13PE cytotoxin has also shown a significant therapeutic effect in preclinical bleomycin or A. fumigatus or Schistosoma mansoni-induced pulmonary pathology including granulomatous fibrosis in mouse models. A clinical study in these diseases has yet to be initiated.

Interleukin-13 receptor alpha2 chain: a potential biomarker and molecular target for ovarian cancer therapy

BACKGROUND

Epithelial ovarian cancer demonstrates high mortality due to diagnosis at an advanced stage. In the search for a biomarker for early diagnosis and a target for therapy, the issue of whether interleukin-13 receptor (IL-13R), shown to be expressed on a variety of human cancers, is expressed in ovarian tumor samples was explored. In addition, whether this receptor serves as a biomarker and can be targeted by IL-13 cytotoxin was examined.

METHODS

IL-13R expression in 15 normal and 68 ovarian tumor tissue samples was determined by immunohistochemistry. Correlation between clinicopathologic features and IL-13R expression was analyzed. The efficacy of IL-13R-directed cytotoxin was determined in mice with subcutaneous, orthotopic, and peritoneal metastatic ovarian cancer.

RESULTS

Immunohistochemical analyses revealed that 83% of ovarian cancer specimens express IL-13Ralpha2, a high-affinity IL-13R subunit chain, whereas normal ovary samples expressed none or very low levels. The majority of clear cell ovarian carcinomas with the worst prognosis showed strong staining for IL-13Ralpha2. IL-13 cytotoxin was highly cytotoxic to the IGROV-1 ovarian cancer cell line in vitro, and it mediated significant antitumor activity against a xenografted tumor model. The antitumor effects were confirmed by treating orthotopically implanted or peritoneal metastatic ovarian tumors, which showed significant extension of survival in immunodeficient mice. IL-13 cytotoxin also prevented cachexia in treated mice. The soluble form of IL-13Ralpha2 was detected in the serum of mice with peritoneal metastasis, and the level decreased to baseline in the treated group.

CONCLUSIONS

IL-13Ralpha2 is a promising target for ovarian cancer therapy, and the soluble form of IL-13R may be a possible surrogate marker for disease monitoring.

Convection-enhanced delivery of interleukin-13 receptor-directed cytotoxin for malignant glioma therapy

The treatment of patients with malignant brain tumors, in particular glioblastoma multiforme (GBM) is very challenging because of their diffuse infiltrative nature and the cytological heterogeneity. The median survival of patients with newly diagnosed GBM is only 12-15 months, and only 8-12% of them survive for two years. Novel approaches for brain tumor therapy are needed. Recently, targeted therapies have emerged as promising modality for cancer targeting. We have discovered that high affinity plasma membrane receptor for interleukin-13 (IL-13), an immune regulatory cytokine, is over-expressed in 60-80% of malignant brain tumors. To target these IL-13R, we generated a chimeric fusion protein, composed of human IL-13 and mutated Pseudomonas exotoxin (PE), termed IL-13 cytotoxin (IL13-PE), and tested its cytotoxicity to IL-13R-expressing GBM cells. IL-13 cytotoxin was highly potent and selective in killing IL-13R-expressing GBM cells. In contrast, normal cells including brain, immune, and endothelial cells were generally not affected by this cytotoxin due to no or low expression of IL-13R. In vivo pre-clinical studies for safety and toxicity were also performed in mice, rats, and monkeys, and IL-13 cytotoxin was found to be well tolerated by both systemic and intracerebral administrations. IL-13 cytotoxin was found to mediate remarkable efficacy in animal models of human brain tumors. Encouraged by these pre-clinical studies, four Phase 1/2 clinical trials in adult patients with recurrent malignant glioma have been completed. These clinical trials involved convection-enhanced delivery (CED) of IL-13 cytotoxin either intratumoral or intraparenchymal after resection of tumor. CED is a novel loco-regional drug delivery method for intracranial tumors that relies on a continuous pressure gradient to distribute drug into interstitial space. This route of IL-13 cytotoxin administration appears to be very well tolerated and have a good risk-benefit profile. Most recently, a randomized controlled Phase 3 clinical trial (PRECISE) with intraparenchymal IL-13 cytotoxin administration was completed and subjects are being monitored for safety and survival.

Differential Regulation of CXCR4 and CCR5 Expression by Interleukin (IL)-4 and IL-13 Is Associated with Inhibition of Chemotaxis and Human Immunodeficiency Virus (HIV) Type 1 Replication But Not HIV Entry into Human Monocytes

Chemokine receptors CXCR4 and CCR5 play a key role in Human Immunodeficiency Virus (HIV) entry into CD4+ monocytic cells. Alteration in the expression levels of these receptors by immunoregulatory cytokines may influence viral entry and hence susceptibility to HIV infection, viral tropism, and disease progression. Helper T cell type 2 (Th2) cytokines interleukin (IL)-4 and IL-13, which share a subunit of their receptor components and exhibit similar biological effects, have been shown to play a key role in HIV infection and disease progression. In this study, we investigated the effects of IL-4 and IL-13 on the expression of CXCR4 and CCR5, and the biological implications of alteration of CXCR4 and CCR5 regulation on monocytic cells with respect to their migration in response to chemokines, HIV entry, and its replication. The results suggest that both IL-4 and IL-13 inhibited the expression of CXCR4, in contrast to CCR5, which was inhibited by IL-13 alone. The downregulation of CXCR4 and CCR5 was correspondingly associated with the inhibition of their respective ligand-induced chemotaxis. Although IL-13 inhibited the expression of both CXCR4 and CCR5, this downregulation of chemokine receptor expression was not sufficient to prevent virus entry. Furthermore, both IL-4 and IL-13 inhibited viral replication in monocytic cells, suggesting that inhibition of chemokine receptor expression per se by these cytokines may not be sufficient to prevent virus entry, and indicating these cytokines may be inhibiting viral replication by targeting pathways subsequent to virus entry.