Structure of and signal transduction through interleukin-4 and interleukin-13 receptors (review)

Ovarian cancer ascites proteomic profile reflects metabolic changes during disease progression

Ovarian cancer (OC) patients develop ascites, an accumulation of ascitic fluid in the peritoneal cavity anda sign of tumour dissemination within the peritoneal cavity. This body fluid is under-researched, mainly regarding the ascites formed during tumour progression that have no diagnostic value and, therefore, are discarded. We performed a discovery proteomics study to identify new biomarkers in the ascites supernatant of OC patients. In this preliminary study, we analyzed a small amount of OC ascites to highlight the importance of not discarding such biological material during treatment, which could be valuable for OC management. Our findings reveal that OC malignant ascitic fluid (MAF) displays a proliferative environment that promotes the growth of OC cells that shift the metabolic pathway using alternative sources of nutrients, such as the cholesterol pathway. Also, OC ascites drained from patients during treatment showed an immunosuppressive environment, with up-regulation of proteins from the signaling pathways of IL-4 and IL-13 and down-regulation from the MHC-II. This preliminary study pinpointed a new protein (Transmembrane Protein 132A) in the OC context that deserves to be better explored in a more extensive cohort of patients' samples. The proteomic profile of MAF from OC patients provides a unique insight into the metabolic kinetics of cancer cells during disease progression, and this information can be used to develop more effective treatment strategies.

Transcriptomics of Parental Care in the Hypothalamic-Septal Region of Female Zebra Finch Brain

(1) Background: The objective of this study was to uncover genomic causes of parental care. Since birds do not lactate and, therefore, do not show the gene expressional changes required for lactation, we investigate gene expression associated with parenting in caring and non-caring females in an avian species, the small passerine bird zebra finch (Taeniopygia guttata). Here, we compare expression patterns in the hypothalamic–septal region since, previously, we showed that this area is activated in parenting females. (2) Methods: Transcriptome sequencing was first applied in a dissected part of the zebra finch brain related to taking care of the nestlings as compared to a control group of social pairs without nestlings. (3) Results: We found genes differentially expressed between caring and non-caring females. When introducing a log2fold change threshold of 1.5, 13 annotated genes were significantly upregulated in breeding pairs, while 39 annotated genes were downregulated. Significant enrichments of dopamine and acetylcholine biosynthetic processes were identified among upregulated pathways, while pro-opiomelanocortin and thyroid hormone pathways were downregulated, suggesting the importance of these systems in parental care. Network analysis further suggested neuro-immunological changes in mothers. (4) Conclusions: The results confirm the roles of several hypothesized major pathways in parental care, whereas novel pathways are also proposed.

Treadmill Exercise Attenuates Cerebral Ischemia-Reperfusion Injury by Promoting Activation of M2 Microglia via Upregulation of Interleukin-4

Background: Exercise has been proven to be an effective therapy for stroke by reducing the microglia-initiated proinflammatory response. Few studies, however, have focused on the phenotypic changes in microglia cells caused by exercise training. The present study was designed to evaluate the influence of treadmill exercise on microglia polarization and the molecular mechanisms involved. Methods: Male Sprague-Dawley rats were randomly assigned into 3 groups: sham, MCAO and exercise. The middle cerebral artery occlusion (MCAO) and exercise groups received MCAO surgery and the sham group a sham operation. The exercise group also underwent treadmill exercise after the surgery. These groups were studied after 4 and 7 days to evaluate behavioral performance using a modified neurological severity score (mNSS), and infarct conditions using 2,3,5-triphenyl tetrazolium chloride. Quantitative real-time polymerase chain reaction (qRT-PCR) and Luminex was employed to determine the expressions of markers of microglia phenotypes. Western blotting was employed to identify the phosphorylation levels of Janus kinase1 (JAK1) and signal transducer and activator of transcription 6 (STAT6). Immunofluorescence was conducted to identify microglia phenotypes. Results: Treadmill exercise was found to improve neurobehavioral outcomes, mainly motor and balance functions, reduce infarct volumes and significantly increase interleukin-4 (IL-4) expression. In addition, treadmill exercise inhibited M1 microglia and promoted M2 microglia activation as evidenced by decreased M1 and increased M2 markers. Furthermore, an obvious increase in p-JAK1 and p-STAT6 was observed in the exercise group. Conclusions: Treadmill exercise ameliorates cerebral ischemia-reperfusion injury by enhancing IL-4 expression to promote M2 microglia polarization, possibly via the JAK1-STAT6 pathway.

Involvement of IL-4, IL-13 and Their Receptors in Pancreatic Cancer

Interleukin (IL)-4 and IL-13 are known as pleiotropic Th2 cytokines with a wide range of biological properties and functions especially in immune responses. In addition, increasing activities have also been determined in oncogenesis and tumor progression of several malignancies. It is now generally accepted that IL-4 and IL-13 can exert effects on epithelial tumor cells through corresponding receptors. Type II IL-4 receptor (IL-4Rα/IL-13Rα1), predominantly expressed in non-hematopoietic cells, is identified to be the main target for both IL-4 and IL-13 in tumors. Moreover, IL-13 can also signal by binding to the IL-13Rα2 receptor. Structural similarity due to the use of the same receptor complex generated in response to IL-4/IL-13 results in overlapping but also distinct signaling pathways and functions. The aim of this review was to summarize knowledge about IL-4 and IL-13 and their receptors in pancreatic cancer in order understand the implication of IL-4 and IL-13 and their receptors for pancreatic tumorigenesis and progression and for developing possible new diagnostic and therapeutic targets.

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

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

Inflammation and pancreatic cancer: An updated review

Pancreatic cancer is a devastating disease with poor prognosis in the modern era. Inflammatory processes have emerged as key mediators of pancreatic cancer development and progression. Recently, studies have been carried out to investigate the underlying mechanisms that contribute to tumorigenesis induced by inflammation. In this review, the role of inflammation in the initiation and progression of pancreatic cancer is discussed.

Analysis of the cancer genome atlas (TCGA) database identifies an inverse relationship between interleukin-13 receptor α1 and α2 gene expression and poor prognosis and drug resistance in subjects with glioblastoma multiforme

Glioblastoma multiforme (GBM) is the most common primary brain tumor in adults. A variety of targeted agents are being tested in the clinic including cancer vaccines, immunotoxins, antibodies and T cell immunotherapy for GBM. We have previously reported that IL-13 receptor subunits α1 and α2 of IL-13R complex are overexpressed in GBM. We are investigating the significance of IL-13Rα1 and α2 expression in GBM tumors. In order to elucidate a possible relationship between IL-13Rα1 and α2 expression with severity and prognoses of subjects with GBM, we analyzed gene expression (by microarray) and clinical data available at the public The Cancer Genome Atlas (TCGA) database (Currently known as Global Data Commons). More than 40% of GBM samples were highly positive for IL-13Rα2 mRNA (Log2 ≥ 2) while only less than 16% samples were highly positive for IL-13Rα1 mRNA. Subjects with high IL-13Rα1 and α2 mRNA expressing tumors were associated with a significantly lower survival rate irrespective of their treatment compared to subjects with IL-13Rα1 and α2 mRNA negative tumors. We further observed that IL-13Rα2 gene expression is associated with GBM resistance to temozolomide (TMZ) chemotherapy. The expression of IL-13Rα2 gene did not seem to correlate with the expression of genes for other chains involved in the formation of IL-13R complex (IL-13Rα1 or IL-4Rα) in GBM. However, a positive correlation was observed between IL-4Rα and IL-13Rα1 gene expression. The microarray data of IL-13Rα2 gene expression was verified by RNA-Seq data. In depth analysis of TCGA data revealed that immunosuppressive genes (such as FMOD, CCL2, OSM, etc.) were highly expressed in IL-13Rα2 positive tumors, but not in IL-13Rα2 negative tumors. These results indicate a direct correlation between high level of IL-13R mRNA expression and poor patient prognosis and that immunosuppressive genes associated with IL-13Rα2 may play a role in tumor progression. These findings have important implications in understanding the role of IL-13R in the pathogenesis of GBM and potentially other cancers.

Endogenously Expressed IL-4Rα Promotes the Malignant Phenotype of Human Pancreatic Cancer In Vitro and In Vivo

Exogenous interleukin-4 (IL-4) has been demonstrated to affect the growth of different human malignancies including pancreatic cancer cells. The aim of our study was to determine the role of endogenously expressed IL-4-receptor-α-chain (IL-4Rα) in pancreatic cancer cells. IL-4Rα-suppression was achieved by generating Capan-1 cells stably expressing shRNA targeting IL-4Rα. The malignant phenotype was characterized by assessing growth properties, directional and non-directional cell movement in vitro and tumor growth in vivo. Signaling pathways were analyzed upon IL-4 and IL-13 stimulation of wildtype (WT) and control-transfected cells compared to IL-4Rα-knockdown cells. Silencing of IL-4Rα resulted in reduced anchorage-dependent cell growth (p < 0.05) and reduced anchorage-independent colony size (p < 0.001) in vitro. Moreover, cell movement and migration was inhibited. IL-4 and IL-13 stimulation of Capan-1-WT cells induced activation of similar pathways like stimulation with Insulin-like growth factor (IGF)-I. This activation was reduced after IL-4Rα downregulation while IGF-I signaling seemed to be enhanced in knockdown-clones. Importantly, IL-4Rα silencing also significantly suppressed tumor growth in vivo. The present study indicates that endogenously expressed IL-4 and IL-4Rα contribute to the malignant phenotype of pancreatic cancer cells by activating diverse pro-oncogenic signaling pathways. Addressing these pathways may contribute to the treatment of the disease.

Evidence of perturbations of the cytokine network in preterm labor

OBJECTIVE

Intraamniotic inflammation/infection is the only mechanism of disease with persuasive evidence of causality for spontaneous preterm labor/delivery. Previous studies about the behavior of cytokines in preterm labor have been largely based on the analysis of the behavior of each protein independently. Emerging evidence indicates that the study of biologic networks can provide insight into the pathobiology of disease and improve biomarker discovery. The goal of this study was to characterize the inflammatory-related protein network in the amniotic fluid of patients with preterm labor.

STUDY DESIGN

A retrospective cohort study was conducted that included women with singleton pregnancies who had spontaneous preterm labor and intact membranes (n = 135). These patients were classified according to the results of amniotic fluid culture, broad-range polymerase chain reaction coupled with electrospray ionization mass spectrometry, and amniotic fluid concentration of interleukin (IL)-6 into the following groups: (1) those without intraamniotic inflammation (n = 85), (2) those with microbial-associated intraamniotic inflammation (n = 15), and (3) those with intraamniotic inflammation without detectable bacteria (n = 35). Amniotic fluid concentrations of 33 inflammatory-related proteins were determined with the use of a multiplex bead array assay.

RESULTS

Patients with preterm labor and intact membranes who had microbial-associated intraamniotic inflammation had a higher amniotic fluid inflammatory-related protein concentration correlation than those without intraamniotic inflammation (113 perturbed correlations). IL-1β, IL-6, macrophage inflammatory protein (MIP)-1α, and IL-1α were the most connected nodes (highest degree) in this differential correlation network (degrees of 20, 16, 12, and 12, respectively). Patients with sterile intraamniotic inflammation had correlation patterns of inflammatory-related proteins, both increased and decreased, when compared to those without intraamniotic inflammation (50 perturbed correlations). IL-1α, MIP-1α, and IL-1β were the most connected nodes in this differential correlation network (degrees of 12, 10, and 7, respectively). There were more coordinated inflammatory-related protein concentrations in the amniotic fluid of women with microbial-associated intraamniotic inflammation than in those with sterile intraamniotic inflammation (60 perturbed correlations), with IL-4 and IL-33 having the largest number of perturbed correlations (degrees of 15 and 13, respectively).

CONCLUSIONS

We report for the first time an analysis of the inflammatory-related protein network in spontaneous preterm labor. Patients with preterm labor and microbial-associated intraamniotic inflammation had more coordinated amniotic fluid inflammatory-related proteins than either those with sterile intraamniotic inflammation or those without intraamniotic inflammation. The correlations were also stronger in patients with sterile intraamniotic inflammation than in those without intraamniotic inflammation. The findings herein could be of value in the development of biomarkers of preterm labor.

The differential expression of IL-4 and IL-13 and its impact on type-2 immunity

Allergic disease represents a significant global health burden, and disease incidence continues to rise in urban areas of the world. As such, a better understanding of the basic immune mechanisms underlying disease pathology are key to developing therapeutic interventions to both prevent disease onset as well as to ameliorate disease morbidity in those individuals already suffering from a disorder linked to type-2 inflammation. Two factors central to type-2 immunity are interleukin (IL)-4 and IL-13, which have been linked to virtually all major hallmarks associated with type-2 inflammation. Therefore, IL-4 and IL-13 and their regulatory pathways represent ideal targets to suppress disease. Despite sharing many common regulatory pathways and receptors, these cytokines perform very distinct functions during a type-2 immune response. This review summarizes the literature surrounding the function and expression of IL-4 and IL-13 in CD4+ T cells and innate immune cells. It highlights recent findings in vivo regarding the differential expression and non-canonical regulation of IL-4 and IL-13 in various immune cells, which likely play important and underappreciated roles in type-2 immunity.

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.

Using haplotype analysis to elucidate significant associations between genes and Hodgkin lymphoma

In this study, we estimated the association between the inferred haplotypes in the inflammation, DNA repair, and folate pathways, and developed risk models for Hodgkin lymphoma. The study population consisted of 200 Hodgkin lymphoma cases and 220 controls. A susceptible association was observed on the XPC gene with haplotype CT (rs2228001 and rs2228000), and a protective association was observed on the IL4R gene with haplotype TCA (rs1805012, rs1805015, and rs1801275). These results can provide the necessary tools to identify high-risk individuals after validation in large data sets.

Regulation of inflammation by interleukin-4: a review of "alternatives"

Studies of IL-4 have revealed a wealth of information on the diverse roles of this cytokine in homeostatic regulation and disease pathogenesis. Recent data suggest that instead of simple linear regulatory pathways, IL-4 drives regulation that is full of alternatives. In addition to the well-known dichotomous regulation of Th cell differentiation by IL-4, this cytokine is engaged in several other alternative pathways. Its own production involves alternative mRNA splicing, yielding at least two functional isoforms: full-length IL-4, encoded by the IL-4 gene exons 1-4, and IL-4δ2, encoded by exons 1, 3, and 4. The functional effects of these two isoforms are in some ways similar but in other ways quite distinct. When binding to the surface of target cells, IL-4 may differentially engage two different types of receptors. By acting on macrophages, a cell type critically involved in inflammation, IL-4 induces the so-called alternative macrophage activation. In this review, recent advances in understanding these three IL-4-related branch points--alternative splicing of IL-4, differential receptor engagement by IL-4, and differential regulation of macrophage activation by IL-4--are summarized in light of their contributions to inflammation.

Challenges in immunotherapy presented by the glioblastoma multiforme microenvironment

Glioblastoma multiforme (GBM) is the most common and aggressive primary brain tumor in adults. Despite intensive treatment, the prognosis for patients with GBM remains grim with a median survival of only 14.6 months. Immunotherapy has emerged as a promising approach for treating many cancers and affords the advantages of cellular-level specificity and the potential to generate durable immune surveillance. The complexity of the tumor microenvironment poses a significant challenge to the development of immunotherapy for GBM, as multiple signaling pathways, cytokines, and cell types are intricately coordinated to generate an immunosuppressive milieu. The development of new immunotherapy approaches frequently uncovers new mechanisms of tumor-mediated immunosuppression. In this review, we discuss many of the current approaches to immunotherapy and focus on the challenges presented by the tumor microenvironment.

IL-12-STAT4-IFN-gamma axis is a key downstream pathway in the development of IL-13-mediated asthma phenotypes in a Th2 type asthma model

IL-4 and IL-13 are closely related cytokines that are produced by Th2 cells. However, IL-4 and IL-13 have different effects on the development of asthma phenotypes. Here, we evaluated downstream molecular mechanisms involved in the development of Th2 type asthma phenotypes. A murine model of Th2 asthma was used that involved intraperitoneal sensitization with an allergen (ovalbumin) plus alum and then challenge with ovalbumin alone. Asthma phenotypes, including airway-hyperresponsiveness (AHR), lung inflammation, and immunologic parameters were evaluated after allergen challenge in mice deficient in candidate genes. The present study showed that methacholine AHR and lung inflammation developed in allergen-challenged IL-4-deficient mice but not in allergen-challenged IL-13-deficient mice. In addition, the production of OVA-specific IgG2a and IFN-gamma-inducible protein (IP)-10 was also impaired in the absence of IL-13, but not of IL-4. Lung-targeted IFN-gamma over-expression in the airways enhanced methacholine AHR and non-eosinophilic inflammation; in addition, these asthma phenotypes were impaired in allergen-challenged IFN-gamma-deficient mice. Moreover, AHR, non-eosinophilic inflammation, and IFN-gamma expression were impaired in allergen-challenged IL-12Rbeta2- and STAT4-deficient mice; however, AHR and non-eosinophilic inflammation were not impaired in allergen-challenged IL-4Ralpha-deficient mice, and these phenomena were accompanied by the enhanced expression of IL-12 and IFN-gamma. The present data suggest that IL-13-mediated asthma phenotypes, such as AHR and non-eosinophilic inflammation, in the Th2 type asthma are dependent on the IL-12-STAT4-IFN-gamma axis, and that these asthma phenotypes are independent of IL-4Ralpha-mediated signaling.

Interleukin-13 and its receptors in idiopathic interstitial pneumonia: clinical implications for lung function

Idiopathic interstitial pneumonia (IIP) is characterized by varying degrees of interstitial fibrosis. IL-13 and IL-4 are strong inducers of tissue fibrosis, whereas IFN-gamma has antifibrotic potential. However, the roles of these substances in IIP remain unknown. IL-13, IL-4, and IFN-gamma were measured in the BAL fluid of 16 idiopathic pulmonary fibrosis (IPF) patients, 10 nonspecific interstitial pneumonia (NSIP) patients, and 8 normal controls. The expression of IL-13 and IL-13Ralpha1/alpha2 in lung tissues was analyzed using ELISA and immunohistochemistry. IL-13 levels were significantly higher in IPF patients than the others (P<0.05). IL-4 levels were higher in both IPF and NSIP patients than in normal controls (P<0.05), and IFN-gamma levels were lower in NSIP patients than in normal controls (P=0.047). IL-13 levels correlated inversely with FVC% (r=-0.47, P=0.043) and DLCO% (r=-0.58, P=0.014) in IPF and NSIP patients. IL-13 was strongly expressed in the smooth muscle, bronchial epithelium, alveolar macrophages and endothelium of IPF patients. IL-13Ralpha1, rather than IL-13Ralpha2, was strongly expressed in the smooth muscle, bronchial epithelium, and endothelium of IPF patients. IL-13 and its receptors may contribute to the pathogenesis of fibrosis in IIP and appear to be related to the severity of the disease.

Phage display selection of peptides that home to atherosclerotic plaques: IL-4 receptor as a candidate target in atherosclerosis

Imaging or drug delivery tools for atherosclerosis based on the plaque biology are still insufficient. Here, we attempted to identify peptides that selectively home to atherosclerotic plaques using phage display. A phage library containing random peptides was ex viv screened for binding to human atheroma tissues. After three to four rounds of selection, the DNA inserts of phage clones wer sequenced. A peptide sequence, CRKRLDRNC, was the most frequently occurring one. Intravenously injected phage displaying the CRKRLDRNC peptide was observed to home to atherosclerotic aortic tissues of low-density lipoprotein receptor-deficient (Ldlr^−/–) mice at higher levels than to normal aortic tissues of wild-type mice. Moreover, a fluorescein- or radioisotope-conjugated synthetic CRKRLDRNC peptide, but not a control peptide, homed in vivo to atherosclerotic plaques in Ldlr^−/– mice, while homing of the peptide to other organs such as brain was minimal. The homing peptide co-localized with endothelial cells, macrophages and smooth muscle cells a mouse and human atherosclerotic plaques. Homology search revealed that the CRKRLDRNC peptide shares a motif of interleukin-receptor (IL-4) that is critical for binding to its receptor. The peptide indeed co-localized with IL-4 receptor (IL-4R) at atherosclerotic plaques. Moreover, the peptide bound to cultured cells expressing IL-4R on the cell surface and the binding was inhibited by the knock-down of IL-4R. These results show that the CRKRLDRNC peptide homes to atherosclerotic plaques through binding to IL-4R as its target and may be a useful tool for selective drug delivery and molecular imaging of atherosclerosis.

Human adrenomedullin up-regulates interleukin-13 receptor alpha2 chain in prostate cancer in vitro and in vivo: a novel approach to sensitize prostate cancer to anticancer therapy

Interleukin-13 (IL-13) receptor alpha2 (IL-13Ralpha2), a high-affinity IL-13 binding subunit and a tumor antigen, is amplified in a variety of human tumor cell lines and tumors in vivo. By cDNA microarray, we have shown that gene transfer of human and rat adrenomedullin (AM) up-regulates IL-13Ralpha2 in a human prostate tumor cell line. Here, we show that IL-13Ralpha2 mRNA and protein are also up-regulated in PC-3 prostate tumor cells by recombinant AM (rAM) and human synthetic AM peptide in a dose-dependent manner in vitro and in vivo in mouse prostate tumor model. The 8- to 10-fold up-regulation of IL-13Ralpha2 by rAM or AM peptide in prostate tumor cells in vitro and in vivo increased their sensitivity to IL-13PE cytotoxin consisting of IL-13 and a truncated form of Pseudomonas exotoxin. Immunodeficient mice with established prostate tumors transfected with AM or treated with AM peptide showed reduction in tumor size by intratumoral administration of IL-13PE in a dose-dependent manner. At the highest dose (three 100 mug/kg/d every alternate day), >70% reduction of tumor size was observed compared with controls (P Collapse

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MESH Headings

• ADP Ribose Transferases/therapeutic use
• Adrenomedullin/analysis
• Adrenomedullin/genetics
• Adrenomedullin/physiology
• Animals
• Bacterial Toxins/therapeutic use
• Cell Line, Tumor
• Exotoxins/therapeutic use
• Gene Expression Regulation, Neoplastic
• Humans
• Immunotoxins/therapeutic use
• Interleukin-13/metabolism
• Interleukin-13/therapeutic use
• Interleukin-13 Receptor alpha2 Subunit/genetics
• Male
• Mice
• Prostatic Neoplasms/drug therapy
• Prostatic Neoplasms/metabolism
• Prostatic Neoplasms/pathology
• RNA, Messenger/analysis
• Up-Regulation
• Virulence Factors/therapeutic use
• Pseudomonas aeruginosa Exotoxin A

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Grants

• Z01 BC005740 Intramural NIH HHS

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Affiliation(s)

Bharat H Joshi Tumor Vaccines and Biotechnology Branch, Division of Cellular and Gene Therapies, Center for Biologics Evaluation and Research, Food and Drug Administration, National Cancer Institute, NIH, Bethesda, Maryland 20892, USA
Pamela Leland
Alfonso Calvo
Jeffrey E Green
Raj K Puri

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Identification of interleukin-13 receptor alpha2 chain overexpression in situ in high-grade diffusely infiltrative pediatric brainstem glioma

Human malignant glioma cell lines and adult brain tumors overexpress high levels of interleukin-13 receptor alpha2 chain (IL-13Ralpha2). Because the IL-13Ralpha2 chain is an important target for cancer therapy and prognosis for patients with brainstem glioma (BSG) remains dismal, we investigated the expression of this receptor in specimens of diffusely infiltrative pediatric BSG relative to normal brain tissue. Twenty-eight BSG specimens and 15 normal brain specimens were investigated for IL-13Ralpha2 protein expression by immunohistochemical analysis (IHC) using two different antibodies in two different laboratories. Highly sensitive Q-dot-based IHC and in situ hybridization (ISH) assays were also developed to identify IL-13Ralpha2 protein and RNA in these specimens. The results were evaluated independently in two laboratories in a blinded fashion. By Q-dot IHC or a standard IHC assay, 17 of 28 (61%) tumor specimens showed modest to strong staining for IL-13Ralpha2, while 15 normal brain tissue samples showed weak expression for IL-13Ralpha2 protein. Significant interrater agreement between the two laboratories was seen in the assessment of IL-13Ralpha2 intensity. High-level IL-13Ralpha2 RNA expression was detected in tumor samples by Q-dot ISH, but only weak RNA expression was observed in normal brain. Significant agreement between ISH and IHC assays was observed (simple kappa [kappa] estimate=0.358, weighted kappa=0.89, p=0.001). IL-13Ralpha2 protein and mRNA are expressed to significantly higher levels in BSG than in normal brain tissue. Both IHC and ISH represent robust methods to detect expression of the IL-13Ralpha2 receptor in BSG that could represent an important new drug target for treatment of this disease.

Interleukin-4 activates large-conductance, calcium-activated potassium (BKCa) channels in human airway smooth muscle cells

Large-conductance, calcium-activated potassium (BK(Ca)) channels are regulated by voltage and near-membrane calcium concentrations and are determinants of membrane potential and excitability in airway smooth muscle cells. Since the T helper-2 (Th2) cytokine, interleukin (IL)-4, is an important mediator of airway inflammation, we investigated whether IL-4 rapidly regulated BK(Ca) activity in normal airway smooth muscle cells. On-cell voltage clamp recordings were made on subconfluent, cultured human bronchial smooth muscle cells (HBSMC). Interleukin-4 (50 ng ml(-1)), IL-13 (50 ng ml(-1)) or histamine (10 microm) was added to the bath during the recordings. Immunofluorescence studies with selective antibodies against the alpha and beta1 subunits of BK(Ca) were also performed. Both approaches demonstrated that HBSMC membranes contained large-conductance channels (>200 pS) with both calcium and voltage sensitivity, all of which is characteristic of the BK(Ca) channel. Histamine caused a rapid increase in channel activity, as expected. A new finding was that perfusion with IL-4 stimulated rapid, large increases in BK(Ca) channel activity (77.2 +/- 63.3-fold increase, P < 0.05, n = 18). This large potentiation depended on the presence of external calcium. In contrast, IL-13 (50 ng ml(-1)) had little effect on BK(Ca) channel activity, but inhibited the effect of IL-4. Thus, HBSMC contain functional BK(Ca) channels whose activity is rapidly potentiated by the cytokine, IL-4, but not by IL-13. These findings are consistent with a model in which IL-4 rapidly increases near-membrane calcium concentrations to regulate BK(Ca) activity.

The role of NKT cells in tumor immunity

NKT cells are a relatively newly recognized member of the immune community, with profound effects on the rest of the immune system despite their small numbers. They are true T cells with a T cell receptor (TCR), but unlike conventional T cells that detect peptide antigens presented by conventional major histocompatibility (MHC) molecules, NKT cells recognize lipid antigens presented by CD1d, a nonclassical MHC molecule. As members of both the innate and adaptive immune systems, they bridge the gap between these, and respond rapidly to set the tone for subsequent immune responses. They fill a unique niche in providing the immune system a cellular arm to recognize lipid antigens. They play both effector and regulatory roles in infectious and autoimmune diseases. Furthermore, subsets of NKT cells can play distinct and sometimes opposing roles. In cancer, type I NKT cells, defined by their invariant TCR using Valpha14Jalpha18 in mice and Valpha24Jalpha18 in humans, are mostly protective, by producing interferon-gamma to activate NK and CD8(+) T cells and by activating dendritic cells to make IL-12. In contrast, type II NKT cells, characterized by more diverse TCRs recognizing lipids presented by CD1d, primarily inhibit tumor immunity. Moreover, type I and type II NKT cells counter-regulate each other, forming a new immunoregulatory axis. Because NKT cells respond rapidly, the balance along this axis can greatly influence other immune responses that follow. Therefore, learning to manipulate the balance along the NKT regulatory axis may be critical to devising successful immunotherapies for cancer.

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.

Identification of core functional region of murine IL-4 using peptide phage display and molecular modeling

Murine IL-4 is a pleiotropic cytokine with undefined core functional region for eliciting downstream signaling. We used molecular modeling to predict the binding sites recognized by an anti-IL-4-neutralizing mAb (11B.11) and peptide phage display to delineate their makeup. The results of these approaches were confirmed by site-directed mutagenesis analysis. The results suggest that the amino acid residues spanning from 79 to 86 (QRLFRAFR) on IL-4 are of the major binding site for 11B.11. Furthermore, the functional experiments demonstrate that the residues R80, R83 and R86, which are located in the helix C of murine IL-4, play a crucial role in binding to the IL-4R alpha-chain. Taken together, a new core functional region of murine IL-4 is identified, which provides new insight into the interaction between IL-4 and IL-4Ralpha. In addition, the results demonstrate that 11B.11 binds to a core functional region of murine IL-4, which prevents this cytokine from interacting with its cognate receptor.

Role for macrophage migration inhibitory factor in asthma

Macrophage migration inhibitory factor (MIF) is an immunologic regulator that is expressed in inflammatory and autoimmune disorders. We investigated MIF's role in asthma using genetic approaches in a mouse model and in a cohort of asthma patients. Mice genetically deficient in MIF that were primed and aerosol-challenged with ovalbumin showed less pulmonary inflammation and lower airway hyperresponsiveness than genetically matched, wild-type controls. MIF deficiency also resulted in lower titers of specific IgE, IgG(1), and IgG(2a), and decreased pulmonary, T(H)2 cytokine levels. IL-5 concentrations were lower and corresponded to decreased eosinophil numbers in bronchoalveolar lavage fluid. T cell studies also showed a lower level of antigen-specific responses in MIF-KO versus wild-type mice. In an analysis of 151 white patients with mild, moderate, or severe asthma (Global Initiative for Asthma criteria), a significant association was found between mild asthma and the low-expression, 5-CATT MIF allele. Pharmacologic inhibition of MIF may be beneficial and could be guided by the MIF genotype of affected individuals.

Analysis of target genes induced by IL-13 cytotoxin in human glioblastoma cells

IL-13 cytotoxin comprised of IL-13 and a mutated form of Pseudomonas exotoxin (fusion protein termed IL-13-PE38QQR) has been shown to inhibit protein synthesis leading to necrotic and apoptotic cell death in glioblastoma cells that express high levels of interleukin-13 receptors (IL-13R). To identify target genes of cell death and other cellular genes with IL-13 receptors in glioblastoma cells, we utilized the cDNA microarrays to analyze global gene expression profiles after IL-13 cytotoxin and IL-13 treatment. IL-13 cytotoxin mediated cytotoxicity to U251 cells in a dose-dependent manner. Hierarchical cluster analysis of differentially expressed genes in U251 glioma cells at different time points after IL-13 cytotoxin treatment showed three major groups, each representing a specific expression pattern. Randomly selected differentially expressed genes from each group were confirmed by RT-PCR analysis. Most down-regulated genes belong to cell adhesion, motility, angiogenesis, DNA repair, and metabolic pathways. While up-regulated genes belong to cell cycle arrest, apoptosis, signaling and various metabolic pathways. Unexpectedly, at early time points, both IL-13 and IL-13 cytotoxin induced several genes belonging to different pathways most notably IL-8, DIO2, END1, and ALDH1A3 indicating that these genes are early response genes and their products may be associated with IL-13R. In addition, IL-13 cytotoxin induced IL-13Ralpha2 mRNA expression during the treatment in glioma cells. Our results indicate that novel cellular genes are involved with IL-13 receptors and that IL-13 cytotoxin induced cell death involves various target genes in human glioblastoma cells. On going studies will determine the role of associated genes and their products in the IL-13R functions in glioma cells.

Mucin biosynthesis: upregulation of core 2 beta 1,6 N-acetylglucosaminyltransferase by retinoic acid and Th2 cytokines in a human airway epithelial cell line

Vitamin A and the T helper 2 cytokines IL-4 and IL-13 play important roles in the induction of mucin gene expression and mucus hypersecretion. However, the effects of these agents on enzymes responsible for mucin glycosylation have received little attention. Here, we report the upregulation of core 2 beta1,6 N-acetylglucosaminyltransferase (C2GnT) activity both by all-trans retinoic acid (RA) and by IL-4 and IL-13 in the H292 airway epithelial cell line. Northern blotting analysis showed that the M isoform of C2GnT, which is expressed in mucus-secreting tissues and can form all mucin glycan beta1,6-branched structures, including core 2, core 4, and blood group I antigen, was upregulated by both RA and IL-4/13. The L isoform, which forms only the core 2 structure, was moderately upregulated by IL-4/13 but not by RA. Enhancement of the M isoform of C2GnT by RA was abolished by an inhibitor of RA receptor alpha, implicating RA receptor alpha in the effect of RA. Likewise, an inhibitor of the Janus kinase 3 pathway blocked the enhancing effects of IL-4/13 on the L and M isoforms of C2GnT, suggesting a role of this pathway in the upregulation of these two C2GnTs by these cytokines. Taken together, the results suggest that IL-4/13 T helper 2 cytokines and RA can alter the activity of enzymes that synthesize branching mucin carbohydrate structure in airway epithelial cells, potentially leading to altered mucin carbohydrate structure and properties.

Hodgkin lymphoma therapy with interleukin-4 receptor-directed cytotoxin in an infiltrating animal model

Hodgkin lymphoma represents unique clinicopathologic features because Hodgkin and Reed-Sternberg (H-RS) cells produce a variety of cytokines, express a variety of cytokine receptors, and are surrounded by numerous nonmalignant immunoreactive cells. We found that receptors for interleukin-4 (IL-4R) are highly expressed in H-RS cells. To target interleukin-4 receptor (IL-4R), we used a recombinant protein fusing circularly permuted human IL-4 and Pseudomonas exotoxin termed IL4(38-37)-PE38KDEL, or IL-4 cytotoxin. The cytotoxic effect of IL-4 cytotoxin on H-RS cell lines was determined to be moderate to high in vitro. We developed an infiltrating model of Hodgkin disease (HD) by injecting an adherent population of HD-MyZ cells subcutaneously into the flanks of beige/nude/X-linked immunodeficient mice. The animal model exhibited spontaneous metastasis of H-RS cells to lymph nodes and dissemination to vital organs, including the lungs. Intraperitoneal or intratumoral treatment of these mice with IL-4 cytotoxin resulted in regression of the primary tumor mass and a decrease in the incidence of lymph node metastasis. Mice injected with HD-MyZ cells demonstrated 203% prolonged survival (mean survival, 63 days) compared with control (mean survival, 31 days) when they received systemic IL-4 cytotoxin treatment. Because numerous H-RS cell lines express receptors for IL-4, IL-4 cytotoxin may be a unique agent for the treatment of Hodgkin lymphoma.

Augmented pulmonary IL-4 and IL-13 receptor subunit expression in idiopathic interstitial pneumonia

BACKGROUND

Some idiopathic interstitial pneumonias (IIPs) are characterised by fibroproliferation and deposition of extracellular matrix. Because efficacious treatment options are limited, research has been directed towards understanding the cytokine networks that may affect fibroblast activation and, hence, the progression of certain IIPs.

AIMS

To examine the expression of interleukin 4 (IL-4), IL-13, and their corresponding receptor subunits in the various forms of IIP and normal patient groups.

METHODS

Molecular and immunohistochemical analysis of IL-4, interferon gamma (IFNgamma), IL-13, IL-4 receptor (IL-R), and IL-13 receptor subunits in surgical lung biopsies (SLBs) from 39 patients (21 usual interstitial pneumonia (UIP), six non-specific interstitial pneumonia (NSIP), eight respiratory bronchiolitic interstitial lung disease (RBILD), and five normal controls).

RESULTS

Molecular analysis demonstrated that IL-13Ralpha2, IL-13Ralpha1, and IL-4Ralpha were present in a greater proportion of upper and lower lobe biopsies from patients with UIP than patients with NSIP and RBILD. Immunohistochemical analysis of patients with UIP, NSIP, and RBILD revealed interstitial staining for all three receptor subunits, whereas such staining was only seen in mononuclear cells present in normal SLBs. Fibroblastic foci in patients with UIP strongly stained for IL-4Ralpha and IL-13Ralpha2. Localised expression of IL-4Ralpha was also seen in SLBs from patients with NSIP but not in other groups.

CONCLUSION

Some histological subtypes of IIP are associated with increased pulmonary expression of receptor subunits responsive to IL-4 and IL-13. These findings may be of particular importance in understanding the pathogenesis of IIP and, more importantly, may provide important novel therapeutic targets.

Specifically targeted killing of interleukin-13 (IL-13) receptor-expressing breast cancer by IL-13 fusion cytotoxin in animal model of human disease

Interleukin-13 receptor (IL-13R) α2 chain binds IL-13 with high affinity and can internalize after binding to ligand. We have exploited this property of IL-13Rα2 chain by receptor-targeted breast cancer therapy. Previous studies have demonstrated that in vivo intratumoral (i.t.) gene transfer of this chain followed by IL-13 cytotoxin [comprised of IL-13 and Pseudomonas exotoxin (IL13-PE38QQR)] therapy causes regression of established human tumors in xenografted models. Breast carcinoma cells do not express IL-13Rα2 chain and are resistant to the antitumor effect of IL-13 cytotoxin. To determine whether IL-13Rα2 chain can render sensitivity of breast cancer to IL-13 cytotoxin, we injected IL-13Rα2 plasmid in s.c. established tumors by i.t. route, followed by systemic or i.t. IL-13 cytotoxin administration. This combination approach showed profound antitumor activity against human breast tumors in xenografted immunodeficient mice. Interestingly, there was dominant infiltration of inflammatory cells in regressing tumors, which were identified to be macrophages producing nitric oxide (NO) and natural killer cells. The partial role of inducible nitric oxide synthase (iNOS)-positive macrophages was confirmed by in vivo macrophage depletion experiments. Serum chemistry, hematology, and organ histology from treated mice did not show any remarkable toxicity resulting from the combination therapy. Taken together, local gene transfer of IL-13Rα2 followed by receptor-targeted IL-13 cytotoxin therapy may be applied safely and effectively to the treatment of localized breast cancer.

Interleukin-13 receptor-directed cytotoxin for malignant glioma therapy: from bench to bedside

Central nervous system malignant neoplasias, in particular, glioblastoma multiforme (GBM) have defied all current therapeutic modalities. New therapies involving tumor targeting approach are being explored. This approach relies on the identification of unique or over-expressed cell surface receptors or antigens on tumor cells. In that regard, we have identified receptor for an immune regulatory cytokine, interleukin-13 (IL-13), which is over-expressed on human malignant glioma cell lines and primary tumor cell cultures. To target IL-13 receptors (IL-13R) for cancer therapy, we have developed a recombinant fusion protein composed of IL-13 and a mutated form of Pseudomonas exotoxin (IL13-PE38QQR or IL-13 cytotoxin). The IL-13 cytotoxin was found to be highly selective and potent in killing human GBM cells in vitro while normal cells including immune cells, endothelial cells and normal brain cells were generally spared the cytotoxic effect of IL-13 cytotoxin. This is because these cells either expressed none or expressed low levels of IL-13R. Consistent with in vitro cytotoxic activity, IL-13 cytotoxin mediated remarkable anti-tumor activity to human glioma in animal xenograft models. The direct injection of IL-13 cytotoxin into subcutaneous human GBM tumors grown in nude mice produced complete and durable regression of established tumors. Intravenous and intraperitoneal administration of IL-13 cytotoxin also reduced tumor burden significantly with fewer complete responders. All animals tolerated therapy well with minimal toxicity to vital organs. Pre-clinical safety and toxicity studies were performed in mice, rats and monkeys. Systemic administration of IL-13 cytotoxin appeared to be well tolerated at high doses (up to 50 microg/kg). Intrabrain parenchyma administration of IL-13 cytotoxin at doses up to 100 microg/ml was very well tolerated without any evidence of gross or microscopic necrosis, whereas at 500 microg/ml dose, localized necrosis was observed in normal rat brain. Based on these encouraging pre-clinical studies, three Phase I/II clinical trials in adults with malignant glioma have been initiated. The first clinical trial involves convection-enhanced delivery (CED) of IL-13 cytotoxin into recurrent malignant glioma. This route of IL-13 cytotoxin administration appears to be fairly well tolerated with no neurotoxicity. The second clinical trial involves infusion of IL-13 cytotoxin by CED following tumor resection. The initial stage of the second study assessed histologic effect of drug administered prior to resection. In third one, IL-13 cytotoxin is infused by CED followed by tumor resection. All three clinical trials are currently ongoing.

Interleukin-4-Pseudomonas exotoxin chimeric fusion protein for malignant glioma therapy

Human malignant glioma cell lines, primary cell cultures, and tumor specimens derived from surgical samples have been shown to overexpress high-affinity receptors (R) for interleukin-4 (IL-4) in vitro and in situ. The significance of IL-4R expression on malignant glioma cells is still unclear. However, IL-4 has been reported to mediate functional effects in several solid tumor cell lines. These activities include inhibition of cell proliferation, regulation of adhesion molecules, and induction of signal transduction through the JAK/STAT pathway. To target IL-4Rs on tumor cells, we have produced a chimeric recombinant fusion protein consisting of a binding ligand, circularly permuted IL-4 and a mutated form of Pseudomonas exotoxin. This molecule is termed IL4(38-37)-PE38KDEL, cpIL4-PE, or IL-4 cytotoxin. Recombinant cpIL4-PE is highly and specifically cytotoxic to glioma cell lines in vitro, while it is not cytotoxic or less cytotoxic to hematopoietic and normal brain cells. In a nude mouse model, cpIL4-PE showed significant antitumor activity and partial or complete regression of small or large established human glioblastoma tumors. Encouraging preclinical efficacy, safety, and tolerability studies lead to testing of this agent in patients with recurrent glioblastoma. Based on these pilot studies, an extended Phase I/II clinical trial is currently ongoing to determine safety, tolerability, and efficacy of cpIL4-PE when injected stereotactically directly into the recurrent glioma by convection enhanced delivery. Preliminary clinical results suggest that cpIL4-PE can cause pronounced necrosis of recurrent glioma tumors without systemic toxicity. The central nervous system toxicities observed were attributed to the volume of infusion and/or nonspecific toxicity. Ongoing clinical trials will reveal antitumor activities of IL-4 cytotoxin in recurrent malignant glioma.

IL-13 and IL-4 promote TARC release in human airway smooth muscle cells: role of IL-4 receptor genotype

The chemokine thymus- and activation-regulated chemokine (TARC) induces selective migration of Th2, but not Th1, lymphocytes and is upregulated in the airways of asthmatic patients. The purpose of this study was to determine whether human airway smooth muscle (HASM) cells produce TARC. Neither IL-4, IL-13, IL-1beta, IFN-gamma, nor TNF-alpha alone stimulated TARC release into the supernatant of cultured HASM cells. However, both IL-4 and IL-13 increased TARC protein and mRNA expression when administered in combination with TNF-alpha but not IL-1beta or IFN-gamma. Macrophage-derived chemokine was not expressed under any of these conditions. TARC release induced by TNF-alpha + IL-13 or TNF-alpha + IL-4 was inhibited by the beta-agonist isoproterenol and by other agents that activate protein kinase A, but not by dexamethasone. To determine whether polymorphisms of the IL-4Ralpha have an impact on the ability of IL-13 or IL-4 to induce TARC release, HASM cells from multiple donors were genotyped for the Ile50Val, Ser478Pro, and Gln551Arg polymorphisms of the IL-4Ralpha. Our data indicate that cells expressing the Val50/Pro478/Arg551 haplotype had significantly greater IL-13- or IL-4-induced TARC release than cells with other IL-4Ralpha genotypes. These data indicate that Th2 cytokines enhance TARC expression in HASM cells in an IL-4Ralpha genotype-dependent fashion and suggest that airway smooth muscle cells participate in a positive feedback loop that promotes the recruitment of Th2 cells into asthmatic airways.

IL-13-induced changes in the goblet cell density of human bronchial epithelial cell cultures: MAP kinase and phosphatidylinositol 3-kinase regulation

In addition to a direct proinflammatory role, IL-13 has been demonstrated to induce a goblet cell metaplastic phenotype in the airway epithelium in vivo. We have studied the direct effects of IL-13 (and IL-4) on well-differentiated, air-liquid interface cultures of human bronchial epithelial cells (HBEs) and provide a quantitative assessment of the development of a mucus hypersecretory phenotype induced by these cytokines. Using Alcian blue staining of goblet cells and immunohistochemical detection of MUC5AC, we found that IL-13 (and IL-4) induced increases in the goblet cell density (GCD) of the HBE cultures. The effects of these cytokines were critically dependent on concentration: 1 ng/ml routinely induced a 5- to 10-fold increase in GCD that was associated with a hypersecretory ion transport phenotype. Paradoxically, 10 ng/ml of either cytokine induced a profound reduction in GCD. Removal of EGF from the culture media or treatment of the cells with AG-1478 [a potent inhibitor of EGF receptor tyrosine kinase (EGFR-TK)] demonstrated that the EGFR-TK pathway was key to the regulation of the basal GCD but that it was not involved in the IL-13-driven increase. The IL-13-driven increase in GCD was, however, sensitive to inhibition of MEK (PD-98059, U-0126), p38 MAPK (SB-202190), and phosphatidylinositol (PtdIns) 3-kinase (LY-294002). These data support the concept that IL-13 is in part able to induce a mucus hypersecretory phenotype through a direct interaction with the airway epithelium and that MAP kinase and PtdIns 3-kinase signaling pathways are involved.

Regulation and function of the interleukin 13 receptor alpha 2 during a T helper cell type 2-dominant immune response

Highly polarized type 2 cytokine responses can be harmful and even lethal to the host if they are too vigorous or persist too long. Therefore, it is important to elucidate the mechanisms that down-regulate these reactions. Interleukin (IL)-13 has emerged as a central mediator of T helper cell (Th)2-dominant immune responses, exhibiting a diverse array of functional activities including regulation of airway hyperreactivity, resistance to nematode parasites, and tissue remodeling and fibrosis. Here, we show that IL-13 receptor (R)alpha2 is a critical down-regulatory factor of IL-13-mediated tissue fibrosis induced by the parasitic helminth Schistosoma mansoni. IL-13Ralpha2 expression was induced after the onset of the fibrotic response, IL-10, IL-13, and Stat6 dependent, and inhibited by the Th1-inducing adjuvant IL-12. Strikingly, schistosome-infected C57BL/6 and BALB/c IL-13Ralpha2-deficient mice showed a marked exacerbation in hepatic fibrosis, despite displaying no change in granuloma size, tissue eosinophilia, or mastocytosis. Fibrosis increased despite the fact that IL-13 levels decreased significantly in the liver and serum. Importantly, pathology was prevented when IL-13Ralpha2-deficient mice were treated with a soluble IL-13Ralpha2-Fc construct, formally demonstrating that their exacerbated fibrotic response was due to heightened IL-13 activity. Together, these studies illustrate the central role played by the IL-13Ralpha2 in the down-regulation of a chronic and pathogenic Th2-mediated immune response.

Interleukin-13 fusion cytotoxin arrests Schistosoma mansoni egg-induced pulmonary granuloma formation in mice

Schistosoma mansoni egg-induced lung pathology requires the actions of interleukin (IL)-4 and IL-13. Because receptors for IL-4 and IL-13 share chains, we examined the effect of a fusion protein comprised of IL-13 and Pseudomonas exotoxin (IL13-PE) on the development of pulmonary granulomas in mice. At day 8 after an intravenous injection of live S. mansoni eggs, whole lung samples from IL13-PE-treated mice exhibited significantly lower IL-4 and IL-13 gene expression, smaller granulomas, decreased collagen levels, and increased IL-13 receptor alpha2 gene expression compared to controls. The therapeutic effects of IL13-PE were also observed at day 16 despite the termination of IL13-PE treatment at day 8. These studies demonstrate that targeting IL-4- and IL-13- responsive cells with IL13-PE effectively arrests S. mansoni egg granuloma formation.

IL-4 receptors on human medulloblastoma tumours serve as a sensitive target for a circular permuted IL-4-Pseudomonas exotoxin fusion protein

Cytotoxins directed to interleukin-4 receptors have shown to mediate relatively selective cytotoxicity against a variety of human cancer cells in vitro and in vivo. In an ongoing Phase I clinical trial, a recombinant protein comprised of circularly permuted IL-4 fused to a mutated form of Pseudomonas exotoxin (the fusion protein termed IL-4(38-37)-PE38KDEL or cpIL4-PE) has shown antitumour activity against malignant glioma. Human medulloblastomas are neuroectodermal tumours that occur in children and have a poor prognosis. The goal of this study was to determine whether human medulloblastoma derived cell lines express interleukin-4 receptor and whether interleukin-4 receptor expression is accompanied by sensitivity to cpIL4-PE. Medulloblastoma cell lines express interleukin-4 receptor at the protein and mRNA levels as determined by binding, indirect immunofluorescence and RT--PCR studies. These cells expressed IL-4Ralpha (also known as IL-4Rbeta) and IL-13Ralpha1 (also known as IL-13Ralpha') chains, however common gamma(c), a component of the interleukin-4 receptor system in immune cells was not detected. Consistent with the expression of IL-4R, cpIL4-PE was found to be highly and specifically cytotoxic to four of five medulloblastoma cell lines. Susceptibility of medulloblastoma cell lines to cpIL4-PE seemed to correlate closely to the functional IL-4 binding sites in general as demonstrated by 125I-IL-4 binding, but did not seem to correlate with mRNA or cell surface immunoreactive receptor protein expression. The sensitivity of medulloblastoma cells to cpIL4-PE could be eliminated by concurrent incubation with IL-4 or IL-13, but not with IL-2. None of these cell lines showed any change in proliferation upon treatment with exogenous IL-4. These studies establish the interleukin-4 receptor as a medulloblastoma-associated target for possible tumour-directed cancer therapy. Further studies are warranted to investigate interleukin-4 receptor expression in primary medulloblastoma tumours and sensitivity to cpIL-4PE in vitro and in vivo.

In vivo overexpression of IL-13 receptor alpha2 chain inhibits tumorigenicity of human breast and pancreatic tumors in immunodeficient mice

Interleukin 13 receptor alpha2 (IL-13R(alpha)2) chain is highly expressed on some tumor cell lines and primary cell cultures. This receptor chain plays an important role in ligand binding and internalization. To determine the functional significance of overexpression of this chain, we stably transfected IL-13R(alpha)2 chain in human breast (MDA-MB-231) and pancreatic (PANC-1) cancer cell lines that naturally do not express this chain. There was no difference in growth between vector only transfected and IL-13R(alpha)2 chain transfected cells in vitro. However, surprisingly, in immunodeficient mice, tumorigenicity was profoundly inhibited in IL-13R(alpha)2 chain overexpressing tumors. Because breast tumors that grew later showed loss of IL-13R(alpha)2 gene expression, lack of tumorigenicity correlated positively with IL-13R(alpha)2 chain expression. Inflammatory cells including neutrophils and macrophages were identified in IL-13R(alpha)2 overexpressing regressing tumors and neutrophils were found to produce IL-13. IL-13 showed a modest antitumor activity to IL-13R(alpha)2 chain overexpressing tumors in vitro and in vivo. Furthermore, IL-13R(alpha)2 chain overexpressing tumors constitutively produced IL-8 that has been shown to have antitumor effect. These results establish a novel function of a cytokine receptor chain and further suggest that the presence of this chain on tumor cells by itself may play a key role in tumorigenicity.

Interleukin-4 rapidly inhibits calcium transients in response to carbachol in bovine airway smooth muscle cells

To assess interleukin (IL)-4 effects on calcium signaling, bovine airway smooth-muscle (ASM) cells were loaded with fura-2 and cytosolic calcium ([Ca(2+)](i)) was measured in single cells by digital microscopy. Human recombinant IL-4 (50 ng/ml) caused small increases in [Ca(2+)](i). For single cells, carbachol-stimulated calcium transients were compared before (S1) and after (S2) exposure to IL-4 or IL-13. When cells were treated with IL-4 (50 ng/ml) for 20 min, the S2/S1 ratio was 0.17 +/- 0.04 (n = 7) even though IL-4 had been washed from the chamber for 10 min before the S2 response. In contrast, controls not treated with IL-4 had S2/S1 of 0.70 +/- 0.04 (n = 13, P < 0.01). Lower concentrations of IL-4 variably decreased transients and IL-13 had no effect. In other experiments, 5 min of IL-4 did not immediately decrease transients but did after a 25-min delay. Goat antihuman IL-4 antibody abolished the effect of IL-4. IL-4 (50 ng/ml) also inhibited responses to caffeine (S2/S1: 0.30 +/- 0.04 and 0.54 +/- 0.06 for IL-4-treated versus control). We conclude that IL-4 rapidly inhibited calcium transients. Because caffeine-stimulated transients were inhibited, IL-4 may act, at least in part, by depleting calcium stores. IL-4 inhibition of cholinergic signaling may be important for modulating ASM responses during inflammation.

Characterization of IL-4 and IL-13 signals dependent on the human IL-13 receptor alpha chain 1: redundancy of requirement of tyrosine residue for STAT3 activation

IL-4 and IL-13 are pleiotropic cytokines whose biological activities overlap with each other. IL-13 receptor alpha chain 1 (IL-13R alpha 1) is necessary for binding to IL-13, and the heterodimer composed of IL-13R alpha 1 and IL-4R alpha chain transduces IL-13 and IL-4 signals; however, the functional mapping of the intracellular domain of IL-13R alpha 1 is not fully understood. In this study, we constructed wild and mutated types of human IL-13R alpha 1, and analyzed IL-4 and IL-13 signals using an IL-13R alpha 1-transfected human B cell line. Expression of IL-13R alpha 1 evoked STAT3 activation by IL-4 and IL-13, and in stimulated human B cells, on which IL-13R alpha 1 was highly expressed, IL-4 and IL-13 induced STAT3 activation. Replacement of the two tyrosine residues completely abolished STAT3 activation, although replacing either tyrosine residue alone retained it. Furthermore, we found that the Box1 region and the C-terminal tail of IL-13R alpha 1 were critical for binding to Tyk2, and activation of Jak1, Tyk2, the insulin receptor substrate-1 and STAT6 respectively. These results suggest that STAT3 activation is involved with IL-4 and IL-13 signals in human B cells along with the activation of STAT6, and that there is a unique sequence in IL-13R alpha 1 to activate STAT3.

Pulmonary expression of interleukin-13 causes inflammation, mucus hypersecretion, subepithelial fibrosis, physiologic abnormalities, and eotaxin production

Interleukin (IL)-13 is a pleiotropic cytokine produced in large quantities by activated CD4(+) Th2 lymphocytes. To define further its potential in vivo effector functions, the Clara cell 10-kDa protein promoter was used to express IL-13 selectively in the lung, and the phenotype of the resulting transgenic mice was characterized. In contrast to transgene-negative littermates, the lungs of transgene-positive mice contained an inflammatory response around small and large airways and in the surrounding parenchyma. It was mononuclear in nature and contained significant numbers of eosinophils and enlarged and occasionally multinucleated macrophages. Airway epithelial cell hypertrophy, mucus cell metaplasia, the hyperproduction of neutral and acidic mucus, the deposition of Charcot-Leyden-like crystals, and subepithelial airway fibrosis were also prominently noted. Eotaxin protein and mRNA were also present in large quantities in the lungs of the transgene-positive, but not the transgene-negative, mice. IL-4, IL-5, granulocyte-macrophage colony-stimulating factor, and monocyte chemoattractant protein-5 were not similarly detected. Physiological evaluations revealed significant increases in baseline airways resistance and airways hyperresponsiveness (AHR) to methacholine in transgene-positive animals. Thus, the targeted pulmonary expression of IL-13 causes a mononuclear and eosinophilic inflammatory response, mucus cell metaplasia, the deposition of Charcot-Leyden-like crystals, airway fibrosis, eotaxin production, airways obstruction, and nonspecific AHR. IL-13 may play an important role in the pathogenesis of similar responses in asthma or other Th2-polarized tissue responses.