N-linked glycosylation of IL-13R alpha2 is essential for optimal IL-13 inhibitory activity

Uncovering novel mechanisms of chitinase-3-like protein 1 in driving inflammation-associated cancers

Chitinase-3-like protein 1 (CHI3L1) is a secreted glycoprotein that is induced and regulated by multiple factors during inflammation in enteritis, pneumonia, asthma, arthritis, and other diseases. It is associated with the deterioration of the inflammatory environment in tissues with chronic inflammation caused by microbial infection or autoimmune diseases. The expression of CHI3L1 expression is upregulated in several malignant tumors, underscoring the crucial role of chronic inflammation in the initiation and progression of cancer. While the precise mechanism connecting inflammation and cancer is unclear, the involvement of CHI3L1 is involved in chronic inflammation, suggesting its role as a contributing factor to in the link between inflammation and cancer. CHI3L1 can aggravate DNA oxidative damage, induce the cancerous phenotype, promote the development of a tumor inflammatory environment and angiogenesis, inhibit immune cells, and promote cancer cell growth, invasion, and migration. Furthermore, it participates in the initiation of cancer progression and metastasis by binding with transmembrane receptors to mediate intracellular signal transduction. Based on the current research on CHI3L1, we explore introduce the receptors that interact with CHI3L1 along with the signaling pathways that may be triggered during chronic inflammation to enhance tumorigenesis and progression. In the last section of the article, we provide a brief overview of anti-inflammatory therapies that target CHI3L1.

Identification and characterisation of novel CAR-T cells to target IL13Rα2 positive human glioma in vitro and in vivo

BACKGROUND

Previously, we discovered that human solid tumours, but not normal human tissues, preferentially overexpress interleukin-13Receptor alpha2, a high binding receptor for IL-13. To develop novel anti-cancer approaches, we constructed a chimeric antigen receptor construct using a high binding and codon optimised scFv-IL-13Rα2 fragment fused with CD3ζ and co-stimulatory cytoplasmic domains of CD28 and 4-1BB.

METHODS

We developed a scFv clone, designated 14-1, by biopanning the bound scFv phages using huIL-13Rα2Fc chimeric protein and compared its binding with our previously published clone 4-1. We performed bioinformatic analyses for complementary determining regions (CDR) framework and residue analyses of the light and heavy chains. This construct was packaged with helper plasmids to produce CAR-lentivirus and transduced human Jurkat T or activated T cells from peripheral blood mononuclear cells (PBMCs) to produce CAR-T cells and tested for their quality attributes in vitro and in vivo. Serum enzymes including body weight from non-tumour bearing mice were tested for assessing general toxicity of CAR-T cells.

RESULTS

The binding of 14-1 clone is to IL-13Rα2Fc-chimeric protein is ∼5 times higher than our previous clone 4-1. The 14-1-CAR-T cells grew exponentially in the presence of cytokines and maintained phenotype and biological attributes such as cell viability, potency, migration and T cell activation. Clone 14-1 migrated to IL-13Rα2Fc and cell free supernatants only from IL-13Rα2+ve confluent glioma tumour cells in a chemotaxis assay. scFv-IL-13Rα2-CAR-T cells specifically killed IL-13Rα2+ve but not IL-13Rα2-ve tumour cells in vitro and selectively caused significant release of IFN-γ only from IL-13Rα2+ve co-cultures. These CAR-T cells regressed IL-13Rα2+ve glioma xenografts in vivo without any general toxicity. In contrast, the IL-13Rα2 gene knocked-down U251 and U87 xenografts failed to respond to the CAR-T therapy.

CONCLUSION

Taken together, we conclude that the novel scFv-IL-13Rα2 CAR-T cell therapy may offer an effective therapeutic option after designing a careful pre-clinical and clinical study.

Interleukin 13 receptor alpha 2 (IL13Rα2): Expression, signaling pathways and therapeutic applications in cancer

Interleukin 13 receptor alpha 2 (IL13Rα2) is increasingly recognized as a relevant player in cancer invasion and metastasis. Despite being initially considered a decoy receptor for dampening the levels of interleukin 13 (IL-13) in diverse inflammatory conditions, accumulating evidences in the last decades indicate the capacity of IL13Rα2 for mediating IL-13 signaling in cancer cells. The biological reasons behind the expression of this receptor with such extremely high affinity for IL-13 in cancer cells remain unclear. Elevated expression of IL13Rα2 is commonly associated with invasion, late stage and cancer metastasis that results in poor prognosis for glioblastoma, colorectal or breast cancer, among others. The discovery of new mediators and effectors of IL13Rα2 signaling has been critical for deciphering its underlying molecular mechanisms in cancer progression. Still, many questions about the effects of inflammation, the cancer type and the tumor degree in the expression of IL13Rα2 remain largely uncharacterized. Here, we review and discuss the current status of the IL13Rα2 biology in cancer, with particular emphasis in the role of inflammation-driven expression and the regulation of different signaling pathways. As IL13Rα2 implications in cancer continue to grow exponentially, we highlight new targeted therapies recently developed for glioblastoma, colorectal cancer and other IL13Rα2-positive tumors.

N-Glycosylation Regulates Chitinase 3-like-1 and IL-13 Ligand Binding to IL-13 Receptor α2

Chitinase 3-like-1 (Chi3l1) and IL-13 are both ligands of IL-13 receptor α2 (IL-13Rα2). The binding of the former activates mitogen-activated protein kinase, AKT, and Wnt/β-catenin signaling, and plays important roles in innate and adaptive immunity, cellular apoptosis, oxidative injury, allergic inflammation, tumor metastasis and wound healing, fibrosis, and repair in the lung. In contrast, the latter binding is largely a decoy event that diminishes the effects of IL-13. Here, we demonstrate that IL-13Rα2 N-glycosylation is a critical determinant of which ligand binds. Structure-function evaluations demonstrated that Chi3l1-IL-13Rα2 binding was increased when sites of N-glycosylation are mutated, and studies with tunicamycin and Peptide:N-glycosidase F (PNGase F) demonstrated that Chi3l1-IL-13Rα2 binding and signaling were increased when N-glycosylation was diminished. In contrast, structure-function experiments demonstrated that IL-13 binding to IL-13Rα2 was dependent on each of the four sites of N-glycosylation in IL-13Rα2, and experiments with tunicamycin and PNGase F demonstrated that IL-13-IL-13Rα2 binding was decreased when IL-13Rα2 N-glycosylation was diminished. Studies with primary lung epithelial cells also demonstrated that Chi3l1 inhibited, whereas IL-13 stimulated, N-glycosylation as evidenced by the ability of Chi3l1 to inhibit and IL-13 to stimulate the subunits of the oligosaccharide complex A and B (STT3A and STT3B). These studies demonstrate that N-glycosylation is a critical determinant of Chi3l1 and IL-13 binding to IL-13Rα2, and highlight the ability of Chi3l1 and IL-13 to alter key elements of the N-glycosylation apparatus in a manner that would augment their respective binding.

Mining Prognostic Biomarkers of Hepatocellular Carcinoma Based on Immune-Associated Genes

This research aims to investigate the immune-associated gene signature from databases to improve the prognostic value in hepatocellular carcinoma (HCC) by multidimensional methods using various bioinformatic methods. Fifty-one immune-associated genes were mined out, which were associated with clinical characters through univariate and multivariate Cox regression analyses, and 51 immune-associated genes could be well-divided HCC samples into high-risk and low-risk clusters. Next, we performed least absolute shrinkage and selection operator (LASSO) Cox regression method to reveal 18 immune-associated genes' signature and calculate risk score of each gene for receiver operating characteristic (ROC) analysis. Comparing with low-risk cluster, high-risk cluster had higher risk score with unfavorable prognosis. Then, multivariate Cox regression analysis showed that risk score of 18 immune-associated genes' signature was associated with tumor invasion and tumor-node-metastasis (TNM) stage. ROC analysis indicated combined TNM stage, and risk score performed more sensitive and specific than single TNM stage or risk score in survival prediction. Furthermore, Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis found that the pathways enriched in tumorigenesis were related to risk score, and those pathways could separate HCC samples into high and low clusters. In addition, the survival prediction of 18 immune-associated genes' signature was well validated in independent test data set, external data set, and Real-time Quantitative PCR (RT-qPCR) experiment. The 18 immune-associated genes' signature was constructed, which could be used in effective prediction of HCC prognosis.

Targeting IL-13Rα2 for effective treatment of malignant peripheral nerve sheath tumors in mouse models

OBJECTIVE

Malignant peripheral nerve sheath tumors (MPNSTs) are aggressive soft tissue sarcomas that harbor a high potential for metastasis and have a devastating prognosis. Combination chemoradiation aids in tumor control and decreases tumor recurrence but causes deleterious side effects and does not extend long-term survival. An effective treatment with limited toxicity and enhanced efficacy is critical for patients suffering from MPNSTs.

METHODS

The authors recently identified that interleukin-13 receptor alpha 2 (IL-13Rα2) is overexpressed on MPNSTs and could serve as a precision-based target for delivery of chemotherapeutic agents. In the work reported here, a recombinant fusion molecule consisting of a mutant human IL-13 targeting moiety and a point mutant variant of Pseudomonas exotoxin A (IL-13.E13 K-PE4E) was utilized to treat MPNST in vitro in cell culture and in an in vivo murine model.

RESULTS

IL-13.E13 K-PE4E had a potent cytotoxic effect on MPNST cells in vitro. Furthermore, intratumoral administration of IL-13.E13 K-PE4E to orthotopically implanted MPNSTs decreased tumor burden 6-fold and 11-fold in late-stage and early-stage MPNST models, respectively. IL-13.E13 K-PE4E treatment also increased survival by 23 days in the early-stage MPNST model.

CONCLUSIONS

The current MPNST treatment paradigm consists of 3 prongs: surgery, chemotherapy, and radiation, none of which, either singly or in combination, are curative or extend survival to a clinically meaningful degree. The results presented here provide the possibility of intratumoral therapy with a potent and highly tumor-specific cytotoxin as a fourth treatment prong with the potential to yield improved outcomes in patients with MPNSTs.

Identification and expression analysis of IL-4/13 receptors in grass carp Ctenopharyngodon idella

Interleukin (IL)-4 and IL-13 are T helper 2 (Th2) cytokines with pleiotropic functions. IL-4 interacts with two receptors consisting of IL-4Rα/γ chain receptor (γC) and IL-4Rα/IL-13Rα1. In contrast, IL-13 binds to IL-13Rα2 but also shares the receptor complex containing IL-4Rα/IL-13Rα1. In fish, two IL-4/13 homologs have been identified but their phylogenetic relationships with IL-4 and IL-13 are ambiguous. In this study, we identified six putative IL-4/13 receptor homologs in grass carp, including γC1, γC2, IL-4Rα1, IL-13Rα1, IL-13Rα2 and a soluble form of IL-4Rα2. Comparative sequence analyses revealed that these receptors possess conserved characteristic domains and the genes encoding them share conserved gene synteny with their human counterparts. All six receptors contain a cytokine binding homology domain (CHD) and two fibronectin type Ⅲ (FNⅢ) like domains, with IL-13Rα1 and IL-13Rα2 harbouring an extra Ig-like domain preceding the CHD domain. Interestingly, grass carp IL-13Rα1 and IL-13Rα2 lack the characteristic WSXWS motif, a typical feature of mammalian type I cytokine receptors. The IL-4/13 receptor genes are differentially expressed in tissues and primary leukocytes of head kidney and can be modulated by Flavobacterium cloumnare (F. cloumnare), suggesting they are involved in immune response against F. cloumnare infection.

Tumor targeted delivery of doxorubicin in malignant peripheral nerve sheath tumors

Peripheral nerve sheath tumors are benign tumors that have the potential to transform into malignant peripheral nerve sheath tumors (MPNSTs). Interleukin-13 receptor alpha 2 (IL13Rα2) is a cancer associated receptor expressed in glioblastoma and other invasive cancers. We analyzed IL13Rα2 expression in several MPNST cell lines including the STS26T cell line, as well as in several peripheral nerve sheath tumors to utilize the IL13Rα2 receptor as a target for therapy. In our studies, we demonstrated the selective expression of IL13Rα2 in several peripheral nerve sheath tumors by immunohistochemistry (IHC) and immunoblots. We established a sciatic nerve MPNST mouse model in NIH III nude mice using a luciferase transfected STS26T MPNST cell line. Similarly, analysis of the mouse sciatic nerves after tumor induction revealed significant expression of IL13Rα2 by IHC when compared to a normal sciatic nerve. IL13 conjugated liposomal doxorubicin was formulated and shown to bind and internalized in the MPNST cell culture model demonstrating cytotoxic effect. Our subsequent in vivo investigation in the STS26T MPNST sciatic nerve tumor model indicated that IL13 conjugated liposomal doxorubicin (IL13LIPDXR) was more effective in inhibiting tumor progression compared to unconjugated liposomal doxorubicin (LIPDXR). This further supports that IL13 receptor targeted nanoliposomes is a potential approach for treating MPNSTs.

Chitinase 3-like 1 regulates cellular and tissue responses via IL-13 receptor α2

Members of the 18 glycosyl hydrolase (GH 18) gene family have been conserved over species and time and are dysregulated in inflammatory, infectious, remodeling, and neoplastic disorders. This is particularly striking for the prototypic chitinase-like protein chitinase 3-like 1 (Chi3l1), which plays a critical role in antipathogen responses where it augments bacterial killing while stimulating disease tolerance by controlling cell death, inflammation, and remodeling. However, receptors that mediate the effects of GH 18 moieties have not been defined. Here, we demonstrate that Chi3l1 binds to interleukin-13 receptor α2 (IL-13Rα2) and that Chi3l1, IL-13Rα2, and IL-13 are in a multimeric complex. We also demonstrate that Chi3l1 activates macrophage mitogen-activated protein kinase, protein kinase B/AKT, and Wnt/β-catenin signaling and regulates oxidant injury, apoptosis, pyroptosis, inflammasome activation, antibacterial responses, melanoma metastasis, and TGF-β1 production via IL-13Rα2-dependent mechanisms. Thus, IL-13Rα2 is a GH 18 receptor that plays a critical role in Chi3l1 effector responses.

Lebrikizumab in the personalized management of asthma

There is a need for improved therapies for severe asthma. Lebrikizumab, a humanized monoclonal antibody that binds to interleukin (IL)-13, is under development for the treatment of poorly controlled asthma. This article reviews the potential role of IL-13 in the pathogenesis of asthma, the efficacy and safety of lebrikizumab in humans, and progress in patient selection for lebrikizumab therapy. IL-13 is a T-helper (Th2) cell-derived cytokine implicated in inflammatory responses in asthma, including serum immunoglobulin-E synthesis, mucus hypersecretion, and subepithelial fibrosis. Blocking the pro-inflammatory effects of IL-13 with lebrikizumab has the potential to improve asthma control. Published data on the efficacy and safety of lebrikizumab in the treatment of asthma are relatively limited. The late asthmatic response after inhaled allergen challenge is reduced by almost 50%, following treatment with lebrikizumab. In a Phase II study performed in 219 adults with poorly controlled asthma despite inhaled corticosteroids (MILLY trial), lebrikizumab produced an improvement in prebronchodilator forced expiratory volume in 1 second of 5.5% compared with placebo at 12 weeks, but had no effects on other efficacy end points. Adverse effects were similar to placebo, except that musculoskeletal side effects occurred slightly more often with lebrikizumab. Stratifying patients into a high Th2 phenotype using serum periostin, which is upregulated in lung epithelial cells by IL-13, may identify individuals responsive to blockade of IL-13. In the MILLY trial, lebrikizumab treatment was associated with greater improvement in lung function in patients with elevated serum periostin levels compared with those with low periostin levels. Two large Phase III randomized controlled trials in patients with uncontrolled asthma are underway to establish the safety and efficacy of lebrikizumab when administered over a 52-week period. These studies will also help to determine whether identifying patients with a Th2 high inflammatory phenotype using serum periostin allows a personalized approach to the treatment of asthma.

Docking protein Gab2 regulates mucin expression and goblet cell hyperplasia through TYK2/STAT6 pathway

Goblet cell hyperplasia (GCH) and mucous hypersecretion are common pathological features of chronic pulmonary diseases, including asthma, chronic obstructive pulmonary disease (COPD), lung cancer, and cystic fibrosis. Despite numerous studies, the molecular basis for this condition remains elusive. Gab2 is a member of the Dos/Gab subfamily scaffolding molecules and plays important roles in regulating growth, differentiation, and inflammation. We found that an elevated level of Gab2 correlates with up-regulated mucus in airway epithelia from patients with lung cancer or COPD, suggesting the potential involvement of Gab2 in pathological lesions in lungs. Knockdown of Gab2 in human airway epithelial cells in vitro decreases IL-13-induced expression of mucin genes. To address the in vivo role of Gab2 in lungs, Gab2-knockout (Gab2(-/-)) mice were sensitized and challenged with ovalbumin (OVA). Further analysis of lungs in an OVA-induced allergy model suggested that GCH and mucus production are remarkably reduced in Gab2(-/-) mice. Mechanistically, Gab2 positively regulates IL-13-induced activation of TYK2/STAT6 by decreasing SOCS3-mediated degradation of TYK2. Together, we define a novel role for Gab2 in mediating mucin gene expression and GCH; these findings have important implications for the pathogenesis and therapy of airway inflammatory diseases.

Characterization and immunotherapeutic implications for a novel antibody targeting interleukin (IL)-13 receptor α2

The high affinity interleukin-13 receptor α2 (IL13Rα2) is selectively expressed at a high frequency by glioblastoma multiforme (GBM) as well as several other tumor types. One approach for targeting this tumor-specific receptor utilizes the cognate ligand, IL-13, conjugated to cytotoxic molecules. However, this approach lacks specificity because the lower affinity receptor for IL-13, IL13Rα1, is widely expressed by normal tissues. Here, we aimed to develop and characterize a novel monoclonal antibody (mAb) specific to IL13Rα2 for the therapeutic purpose of targeting IL13Rα2-expressing tumors. Hybridoma cell lines were generated and compared for binding affinities to recombinant human IL13Rα2 (rhIL13Rα2). Clone 47 demonstrated binding to the native conformation of IL13Rα2 and was therefore chosen for further studies. Clone 47 bound specifically and with high affinity (K(D) = 1.39 × 10(-9) M) to rhIL13Rα2 but not to rhIL13Rα1 or murine IL13Rα2. Furthermore, clone 47 specifically recognized wild-type IL13Rα2 expressed on the surface of CHO and HEK cells as well as several glioma cell lines. Competitive binding assays revealed that clone 47 also significantly inhibited the interaction between human soluble IL-13 and IL13Rα2 receptor. Moreover, we found that N-linked glycosylation of IL13Rα2 contributes in part to the interaction of the antibody to IL13Rα2. In vivo, the IL13Rα2 mAb improved the survival of nude mice intracranially implanted with a human U251 glioma xenograft. Collectively, these data warrant further investigation of this novel IL13Rα2 mAb with an emphasis on translational implications for therapeutic use.

Equilibrium and kinetic analysis of human interleukin-13 and IL-13 receptor alpha-2 complex formation

Interleukin 13 (IL-13) is a pleiotropic cytokine secreted by activated T cells. Both IL-13 and its polymorphic variant (IL-13-R110Q) have been shown to be associated with multiple diseases such as asthma and allergy. Two IL-13 receptors have been identified, IL-13R alpha-1 receptor (IL-13Rα1) and IL-13R alpha-2 receptor (IL-13Rα2). It has been well established that IL-13 binds to IL-13Rα1 alone with low nM affinity while binding to the IL-13Rα1/IL-4R receptor complex is significantly tighter (pM). The affinity between IL-13 and IL-13Rα2, however, remains elusive. Several values have been reported in the literature varying from 20 pM to 2.5 nM. The affinities previously reported were obtained using surface plasmon resonance (SPR) or Scatchard analysis of (125) I-IL-13 binding data. This report presents the results for the kinetics and equilibrium binding analysis studies performed using label-free kinetic exclusion assay (KEA) for the interaction of human IL-13 and IL-13Rα2. KEA equilibrium analysis showed that the affinities of IL-13Rα2 are 107 and 56 pM for IL-13 and its variant (IL-13-R110Q), respectively. KEA kinetic analysis showed that a tight and very stable complex is formed between IL-13Rα2 and IL-13, as shown by calculated dissociation rate constants slower than 5 × 10(-5) per second. Kinetic analysis also showed significant differences in the kinetic behavior of wild type (wt) versus IL-13-R110Q. IL-13-R110Q not only associates to IL-13Rα2 slower than wt human IL-13 (wt-IL-13), as previously reported, but IL-13-R110Q also dissociates slower than wt-IL-13. These results show that IL-13Rα2 is a high affinity receptor and provide a new perspective on kinetic behavior that could have significant implications in the understanding of the role of IL-13-R110Q in the disease state.

Interleukins, from 1 to 37, and interferon-γ: receptors, functions, and roles in diseases

Advancing our understanding of mechanisms of immune regulation in allergy, asthma, autoimmune diseases, tumor development, organ transplantation, and chronic infections could lead to effective and targeted therapies. Subsets of immune and inflammatory cells interact via ILs and IFNs; reciprocal regulation and counter balance among T(h) and regulatory T cells, as well as subsets of B cells, offer opportunities for immune interventions. Here, we review current knowledge about ILs 1 to 37 and IFN-γ. Our understanding of the effects of ILs has greatly increased since the discoveries of monocyte IL (called IL-1) and lymphocyte IL (called IL-2); more than 40 cytokines are now designated as ILs. Studies of transgenic or knockout mice with altered expression of these cytokines or their receptors and analyses of mutations and polymorphisms in human genes that encode these products have provided important information about IL and IFN functions. We discuss their signaling pathways, cellular sources, targets, roles in immune regulation and cellular networks, roles in allergy and asthma, and roles in defense against infections.

Airway fibroblasts in asthma manifest an invasive phenotype

RATIONALE

Invasive cell phenotypes have been demonstrated in malignant transformation, but not in other diseases, such as asthma. Cellular invasiveness is thought to be mediated by transforming growth factor (TGF)-β1 and matrix metalloproteinases (MMPs). IL-13 is a key T(H)2 cytokine that directs many features of airway remodeling through TGF-β1 and MMPs.

OBJECTIVES

We hypothesized that, in human asthma, IL-13 stimulates increased airway fibroblast invasiveness via TGF-β1 and MMPs in asthma compared with normal controls.

METHODS

Fibroblasts were cultured from endobronchial biopsies in 20 subjects with mild asthma (FEV(1): 90 ± 3.6% pred) and 17 normal control subjects (FEV(1): 102 ± 2.9% pred) who underwent bronchoscopy. Airway fibroblast invasiveness was investigated using Matrigel chambers. IL-13 or IL-13 with TGF-β1 neutralizing antibody or pan-MMP inhibitor (GM6001) was added to the lower chamber as a chemoattractant. Flow cytometry and immunohistochemistry were performed in a subset of subjects to evaluate IL-13 receptor levels.

MEASUREMENTS AND MAIN RESULTS

IL-13 significantly stimulated invasion in asthmatic airway fibroblasts, compared with normal control subjects. Inhibitors of both TGF-β1 and MMPs blocked IL-13-induced invasion in asthma, but had no effect in normal control subjects. At baseline, in airway tissue, IL-13 receptors were expressed in significantly higher levels in asthma, compared with normal control subjects. In airway fibroblasts, baseline IL-13Rα2 was reduced in asthma compared with normal control subjects.

CONCLUSIONS

IL-13 potentiates airway fibroblast invasion through a mechanism involving TGF-β1 and MMPs. IL-13 receptor subunits are differentially expressed in asthma. These effects may result in IL-13-directed airway remodeling in asthma.

Two copies of the genes encoding the subunits of putative interleukin (IL)-4/IL-13 receptors, IL-4Rα, IL-13Rα1 and IL-13Rα2, have been identified in rainbow trout (Oncorhynchus mykiss) and have complex patterns of expression and modulation

Mammalian interleukin-4 (IL-4) and IL-13 are T helper type 2 (Th2) cytokines with pleiotropic functions in immunity. They signal through receptors containing IL-4Rα and IL-2Rγ or IL-13Rα1. In addition, a decoy receptor, IL-13Rα2, is known to exist and modulates the function of IL-13. The existence of fish orthologues to mammalian IL-4 and IL-13 is still under debate. However, the receptor chains have been predicted in zebrafish, and we have previously cloned IL-2Rγ and IL-13Rα2 in rainbow trout. In this study, we have cloned a further five novel trout IL-4/13 receptors. Thus, each of the IL-4Rα, IL-13Rα1 and IL-13Rα2 chains has two copies. The identities of the receptors is supported by homology analysis, characteristic domain structure, phylogenetic tree analysis and synteny analysis in zebrafish. However, the characteristic WSXWS motif of structural importance in mammalian type I cytokine receptors is missing in all fish IL-4Rα and IL-13Rα1 molecules. All the receptors have a characteristic domain structure that is similar to their mammalian counterparts except for IL-13Rα1b that has the N-terminal Ig domain missing. Since this Ig domain is a specific and critical binding unit for IL-13 but not for IL-4 signalling, its absence potentially converts the IL-13Rα1b into a receptor that can only signal via IL-4 ligation. The existence of duplicated receptor genes perhaps suggests that more ligands still remain to be discovered that will bind these receptors. The duplicated receptors are differentially expressed in most tissues and cell lines examined, and their expression can be modulated by LPS, polyIC and IFN-γ in cell lines. In contrast, the T-cell stimulant phytohaemagglutinin increased the expression of IL-4Rα1 and IL-4Rα2, but not IL-13Rα1/2, suggesting a role of an IL-4-like molecule in T-cell growth/activation in fish.

Interleukin-13 receptor α2 DNA prime boost vaccine induces tumor immunity in murine tumor models

Background

DNA vaccines represent an attractive approach for cancer treatment by inducing active T cell and B cell immune responses to tumor antigens. Previous studies have shown that interleukin-13 receptor α2 chain (IL-13Rα2), a tumor-associated antigen is a promising target for cancer immunotherapy as high levels of IL-13Rα2 are expressed on a variety of human tumors. To enhance the effectiveness of DNA vaccine, we used extracellular domain of IL-13Rα2 (ECDα2) as a protein-boost against murine tumor models.

Methods

We have developed murine models of tumors naturally expressing IL-13Rα2 (MCA304 sarcoma, 4T1 breast carcinoma) and D5 melanoma tumors transfected with human IL-13Rα2 in syngeneic mice and examined the antitumor activity of DNA vaccine expressing IL-13Rα2 gene with or without ECDα2 protein mixed with CpG and IFA adjuvants as a boost vaccine.

Results

Mice receiving IL-13Rα2 DNA vaccine boosted with ECDα2 protein were superior in exhibiting inhibition of tumor growth, compared to mice receiving DNA vaccine alone, in both prophylactic and therapeutic vaccine settings. In addition, prime-boost vaccination significantly prolonged the survival of mice compared to DNA vaccine alone. Furthermore, ECDα2 booster vaccination increased IFN-γ production and CTL activity against tumor expressing IL-13Rα2. The immunohistochemical analysis showed the infiltration of CD4 and CD8 positive T cells and IFN-γ-induced chemokines (CXCL9 and CXCL10) in regressing tumors of immunized mice. Finally, the prime boost strategy was able to reduce immunosuppressive CD4⁺CD25⁺Foxp3⁺ regulatory T cells (Tregs) in the spleen and tumor of vaccinated mice.

Conclusion

These results suggest that immunization with IL-13Rα2 DNA vaccine followed by ECDα2 boost mixed with CpG and IFA adjuvants inhibits tumor growth in T cell dependent manner. Thus our results show an enhancement of efficacy of IL-13Rα2 DNA vaccine with ECDα2 protein boost and offers an exciting approach in the development of new DNA vaccine targeting IL-13Rα2 for cancer immunotherapy.

Differential expression of the alpha2 chain of the interleukin-13 receptor in metastatic human prostate cancer ARCaPM cells

BACKGROUND

The alpha2 chain of the interleukin-13 receptor (IL13Ralpha2) is a high-affinity receptor and a candidate target for cytotoxic killing of cancer cells. Availability of a human prostate cancer cell line with high level of IL13Ralpha2 expression will facilitate the development of therapeutic modalities.

METHODS

ARCaP(E) and ARCaP(M) human prostate cancer cell lines were subjected to comparative analyses of gene expression. Expression of the IL13Ralpha2 protein was confirmed by Western blotting and immunostaining. IL13Ralpha2 proteins in xenograft tumors and clinical human prostate cancer specimens were detected by specific antibodies. LNCaP prostate cancer cells stably transfected with IL13Ralpha2 were examined for accelerated growth in athymic mice.

RESULTS

We found that IL13Ralpha2 proteins could be detected in both the ARCaP(E) and ARCaP(M) cells, but the expression level in ARCaP(M) was more than 17-fold higher than in ARCaP(E) cells. Importantly, the ARCaP lineage represented the only human prostate cancer cell line that expresses IL13Ralpha2 proteins at the level detectable by Western blotting. Expression of IL13Ralpha2 was accompanied by resistance to the anti-tumor activity of interleukin-13 (IL-13). ARCaP cells were found to be insensitive to growth inhibition upon IL-13 treatment, while overexpression of IL13Ralpha2 in LNCaP cells promoted intratibial tumor growth in athymic mice.

CONCLUSIONS

Differential IL13Ralpha2 expression may account for the high tumorigenic and metastatic potential of ARCaP(M) cells. The unique expression of IL13Ralpha2 makes ARCaP lineage an attractive model for evaluating the targeting efficacy of therapeutic agents based on IL13Ralpha2 protein expression.

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.

Targeting IL-13Ralpha2-positive cancer with a novel recombinant immunotoxin composed of a single-chain antibody and mutated Pseudomonas exotoxin

We have shown previously that high-affinity receptors for interleukin-13 (IL-13Ralpha2) are overexpressed on a variety of solid cancer cells, diseased fibroblasts, and other cells, and a chimeric fusion protein composed of human IL-13 and mutated Pseudomonas exotoxin (IL-13-PE38) is highly and specifically cytotoxic to these cells in vitro and in vivo. To improve the specificity for the target, we isolated specific antibodies against IL-13Ralpha2 from human single-chain Fv (scFv) antibody phage library and developed immunotoxin by selecting two high-affinity clones of scFv and fused to PE. The fusion chimeric gene was expressed in Escherichia coli, and highly purified IL-13R-specific immunotoxin, termed anti-IL-13Ralpha2(scFv)-PE38, was tested for its cytotoxicity. This molecule was highly cytotoxic to U251 glioma and PM-RCC renal cell carcinoma cell lines in vitro. The cytotoxic activity was neutralized by purified extracellular domain of IL-13Ralpha2 but not by IL-13, indicating that cytotoxic activity is specific. Anti-IL-13Ralpha2(scFv)-PE38 showed significant antitumor activity in immunodeficient mice with s.c. glioma tumors. Both i.p. and i.t. routes of administration showed antitumor activity in a dose-dependent manner. The maximum tolerated dose of anti-IL-13Ralpha2(scFv)-PE38 was 200 microg/kg i.p. twice daily for 5 days. These results indicate that anti-IL-13Ralpha2(scFv)-PE38 is a highly selective therapeutic agent for cancer therapy and should be further tested in animal models of human cancer.

Matrix metalloproteinase 8 contributes to solubilization of IL-13 receptor alpha2 in vivo

BACKGROUND

IL-13 receptor alpha2 (IL-13R alpha 2) is a high-affinity receptor for IL-13, a central mediator of allergic asthma. It acts predominantly as a decoy receptor but can also contribute to IL-13 responses under certain conditions. IL-13R alpha 2 exists in soluble and membrane forms, which can both bind IL-13 and modulate its activity. Yet the proteolytic processes that contribute to the generation of soluble IL-13R alpha 2 are largely unknown.

OBJECTIVE

We sought to investigate the role of matrix metalloproteinases (MMPs) in the generation of soluble IL-13R alpha 2.

METHODS

Acellular cleavage assays by MMPs were performed by using glutathione-S-transferase fusion proteins of murine or human IL-13R alpha 2. IL-13R alpha 2 stable-transfected cells were used for analysis of surface expression and release of soluble IL-13R alpha 2. Wild-type and MMP-8-deficient mice were used for analysis of allergen-induced airway hyperresponsiveness and solubilization of IL-13R alpha 2.

RESULTS

Among several MMPs tested, only MMP-8 cleaved IL-13R alpha 2. Treatment of transfected human or murine cells expressing high levels of surface IL-13R alpha 2 with MMP-8 resulted in release of soluble IL-13R alpha 2 into the supernatants, with a concomitant decrease in surface IL-13R alpha 2 levels. The IL-13R alpha 2 solubilized by MMP-8 retained IL-13 binding activity. In an asthma model MMP-8-deficient mice displayed increased airway hyperresponsiveness and decreased soluble IL-13R alpha 2 protein levels in bronchoalveolar lavage fluid compared with those seen in wild-type mice after house dust mite challenge.

CONCLUSION

MMP-8 cleaves IL-13R alpha 2 in vitro and contributes to the solubilization of IL-13R alpha 2 in vivo.

Expression of human IL-13 receptor α2 extracellular domain in Pichia pastoris

Interleukin-13 receptor alpha2 (IL-13Ralpha2) binds IL-13 with high affinity and plays an important role in IL-13 signaling as a decoy receptor. We expressed the extracellular domain of human IL-13Ralpha2 (1-313) in methylotrophic yeast Pichia pastoris. SDS-PAGE analysis by PAS staining and Western blot analysis detected the product of the extracellular domain of human IL-13Ralpha2 as glycoprotein from P. pastoris. The yield of purified extracellular domain of human IL-13Ralpha2 was 2mg from 1L of culture. From CD analysis, the 2D structure of the purified IL-13Ralpha2 showed the typical beta-sheet. ELISA of the purified IL-13Ralpha2 detected the binding activity for human IL-13. Thus, it was found that the active extracellular domain of human IL-13Ralpha2 was expressed from P. pastoris.

IL-13 receptor isoforms: breaking through the complexity

Interleukin (IL)-13 is an immunoregulatory cytokine secreted predominantly by activated T-helper type 2 (Th2) cells, and it has been identified as crucial in developing allergic inflammatory responses. Its diverse functions are mediated by a complex receptor system including IL-4 receptor alpha (IL-4Ralpha; CD124) and two other cognate cell surface proteins, IL-13Ralpha1 (CD213a1) and IL-13Ralpha2 (CD213a2). IL-13Ralpha1 forms a heterodimer with IL-4Ralpha that is a signaling IL-13 receptor. In contrast, IL-13Ralpha2 has been thought to be a decoy receptor due to its short cytoplasmic tail. IL-13Ralpha2 exists on the cell membrane, intracellularly, and in soluble form. Recent reports revealed that membrane IL-13Ralpha2 may have some signaling capabilities, and soluble IL-13Ralpha2 is a critical endogenous modulator for IL-13 responses. The receptor has more complicated functions than a simple decoy receptor. In this review, we describe the isoforms of IL-13Ralpha2 and discuss newly revealed functions of IL-13Ralpha2.

Endogenous metalloprotease solubilizes IL-13 receptor alpha2 in airway epithelial cells

IL-13 receptor alpha2 (IL-13Ralpha2) has been postulated to be a decoy receptor. The precise mechanisms for the generation of soluble IL-13Ralpha2 and the biological activity of the endogenous soluble form have not been reported. Hypothesizing that the soluble form of IL-13Ralpha2 is generated by proteolytic cleavage of membrane-bound receptors, we transfected human airway epithelial cells with adenoviral vectors encoding full-length IL-13Ralpha2. Eotaxin production from IL-13Ralpha2-transfected cells was suppressed, and soluble IL-13Ralpha2 in the supernatants was increased time-dependently after the transfection. The transfer of conditioned media from IL-13Ralpha2-transfected cells inhibited IL-13-induced eotaxin production and STAT6 phosphorylation in non-transfected cells. PMA enhanced the release of soluble IL-13Ralpha2, and metalloprotease inhibitors inhibited this release. These findings suggest that airway epithelial cells with upregulation of membrane-bound IL-13Ralpha2 secrete soluble IL-13Ralpha2 into its supernatant, causing the autocrine and paracrine downregulation of the IL-13/STAT6 signal. Metalloprotease(s) are responsible for the proteolytic cleavage of cell surface IL-13Ralpha2.