Mechanism of action of interleukin-13 antagonist (IL-13E13K) in cells expressing various types of IL-4R

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.

The potential for genetically altered microglia to influence glioma treatment

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

IL-4 analogues with site-specific chemical modification at position 121 inhibit IL-4 and IL-13 biological activities

IL-4 signaling into a cell occurs via assembly of a receptor complex that consists of a high-affinity IL-4Rα chain and a low affinity chain, where the low-affinity chain is either γc or IL-13Rα1. It has been previously shown that mutational disruption of the low affinity interface in the IL-4DM (double mutein) yields an antagonist that inhibits IL-4 as well as IL-13-dependent responses. The present study reveals that new types of IL-4 antagonists can be generated by site-specific chemical modification. The chemically modified IL-4 analogues consist of (1) mixed disulfides created by refolding IL-4 cysteine muteins in the presence of different thiol compounds or (2) maleimide conjugates created by modifying cysteine muteins with maleimide derivatives. IL-4 analogues chemically modified at position 121 retain marginal binding affinity to γc or IL-13Rα1 receptor ectodomains during SPR interaction analysis. The biological activity of the analogues is strongly reduced in HEK-Blue IL-4/IL-13 cells as well as in Jurkat cells. Since the IL-4 analogues modified at position 121 have the ability to inhibit γc (IL-4)- and IL13Rα1 (IL-4/IL-13)-dependent responses in Jurkat and HEK-Blue cell lines, they effectively act as IL-4 antagonists. The results of our IL-4 study provide the first example of a cytokine that is transformed into a competitive inhibitor by site-specific chemical modification.

Upregulation of Toll-like receptor (TLR) expression and release of cytokines from P815 mast cells by GM-CSF

Backgroud

Recently, mast cells have been recognized to express several Toll-like receptors (TLRs) on their membrane surfaces, and granulocyte-macrophage colony-stimulating factor (GM-CSF) was reported to be able to alter expression of TLRs and cytokine production in neutrophils. However, whether GM-CSF modulates the expression of TLR and cytokine production in mast cells is not clear.

Results

Using flow cytometry and real time PCR techniques, we found that GM-CSF upregulated expression of TLR3 and TLR7 in P815 cells in a concentration dependent manner. GM-CSF also provoked approximately up to 2.4 and 2.3 fold increase in IL-13 and IL-6 release from P815 cells, respectively following 16 h incubation. GM-CSF induced IL-13 secretion, TLR3 and TLR7 expression appeared to be through activation of mitogen-activated protein kinase (MAPK) and phosphotidylinositol 3-kinase (PI3K)/Akt signaling pathways, whereas GM-CSF elicited IL-6 release seemed via Akt signaling pathway. At 10 ng/ml, GM-CSF significantly enhanced R-848-induced IL-6 release from P815 cells.

Conclusion

The ability of GM-CSF in modulation of expression of TLR3 and TLR7 in P815 mast cells and in stimulation of IL-13 and IL-6 release from P815 mast cells in vitro suggests that GM-CSF might play an important role in enhancing the innate immune responses of mast cell to viral infection

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.

Interleukin 13 and the beta-adrenergic blockade theory of asthma revisited 40 years later

BACKGROUND

Beta2-Adrenergic agonists are the most potent agents clinically used in inhibiting and preventing the immediate response to bronchoconstricting agents and in inhibiting mast cell mediator release. This raises the possibility that an abnormality in beta-adrenergic receptor function or circulating catecholamine levels could contribute to airway hyperresponsiveness.

OBJECTIVE

To link interleukin 13 (IL-13) to the pathogenesis of asthma.

METHODS

Almost 4 decades ago, Andor Szentivanyi published a beta-adrenergic theory of atopic abnormality in bronchial asthma. He proposed 9 characteristics to define bronchial asthma. Because he published these 9 tenets of the beta-adrenergic blockade theory of asthma in 1968, it is appropriate and important to evaluate their relevance in light of advances in pharmacology, inflammation, and immunology.

RESULTS

We describe the effects of the allergic reaction on beta-adrenergic responses and airway responsiveness. Both IL-1beta and tumor necrosis factor a have been detected in increased amounts in bronchial lavage fluids in allergic airway inflammation. Both IL-13 and the proinflammatory cytokines IL-1beta and tumor necrosis factor a have been demonstrated in airway smooth muscle to cause a decreased relaxation response to beta-adrenergic agonist. However, IL-13 has been shown to be necessary and sufficient to produce the characteristics of asthma.

CONCLUSION

The decreased adrenergic bronchodilator activity and associated hypersensitivity to mediators put forth by Szentivanyi can be elicited with IL-13 and support its role in the pathogenesis of asthma.

Novel recombinant adenoviral vector that targets the interleukin-13 receptor alpha2 chain permits effective gene transfer to malignant glioma

Transduction of malignant glioma with adenovirus serotype 5 (Ad5) vectors is limited by the low levels of coxsackievirus and adenovirus receptor (CAR) on tumor cells. However, malignant brain tumors have been found to overexpress a glioma-associated receptor, interleukin-13 receptor alpha2 chain (IL-13Ralpha2), a marker of both glial transformation and tumor grade. To selectively target Ad5 to IL-13Ralpha2, we constructed a replication-deficient adenoviral vector that possesses an IL-13 ligand presented by a T4 phage fibritin shaft, and designated the new virus LU-13. Western blot and sequence analyses confirmed proper trimerization and ligand presentation by the T4 fibritin shaft. Confocal microscopy analysis of primary glioma suspensions incubated with viral recombinants showed that LU-13 colocalized with IL-13Ralpha2. Luciferase transduction assays conducted in both primary and passaged glioma cell cultures exhibited at least 10-fold enhanced gene transduction. Moreover, the virus preferentially bound to glioma cells, as documented by increased adenoviral E4 DNA copy number. In vitro competition assays performed with anti-human IL-13 monoclonal antibody confirmed significant attenuation of LU-13 transduction. These results were further confirmed in vivo, where LU-13 showed a 300-fold increase in transgene expression. In summary, we describe here the development of a novel and targeted adenoviral vector that binds IL-13Ralpha2. Our findings confirm the ability of LU-13 to bind IL-13Ralpha2 and increase transgene expression, making it an attractive gene therapy vector for the treatment of malignant glioma in a clinical setting.

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

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

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

A high-affinity receptor for interleukin (IL)-13 (interleukin-13R alpha 2) is over-expressed in disease-related fibroblasts and neoplastic cells and is involved in cancer, allergic, and inflammatory diseases. The extracellular domain of IL-13R alpha2 (ECD alpha2) could be cleaved, which serves as a decoy receptor. We have expressed and purified ECD alpha2 in both Escherichia coli (E. coli) and mammalian systems as a soluble fragment and studied its biological activities. Although both products of ECD alpha2 showed IL-13 inhibitory activities, mammalian cell-derived ECD alpha2 appeared to be superior compared with purified protein from E. coli. When expressed in E. coli, ECD alpha2 appeared to be a monomer of 42 but a 60 kDa protein when purified from mammalian cells due to heavy glycosylation. The purified glycosylated ECD alpha2 efficiently inhibited IL-13-induced STAT6 phosphorylation in immune and Hodgkin's lymphoma cell lines, IL-13 binding, and cytotoxicity of IL-13 cytotoxin in various cancer cell lines. The improved potency of mammalian cell-derived ECD alpha2 was shown over ECD alpha2/Fc fusion protein. The N-linked glycosylation of ECD alpha2 was found to be essential for optimal IL-13 inhibitory activity as deglycosylation by PNGase F showed lower activity. ECD alpha2 did not inhibit IL-4-induced STAT6 phosphorylation, indicating that inhibitory effects of ECD alpha2 are receptor specific. These results indicate that glycosylated ECD alpha2 can serve as a potent inhibitor of IL-13 in a variety of conditions in which IL-13 is a key mediator, e.g., pulmonary, allergic, fibrotic, and neoplastic diseases.

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

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

IL-4 receptor alpha is an important modulator of IL-4 and IL-13 receptor binding: implications for the development of therapeutic targets

IL-4 is a key cytokine associated with allergy and asthma. Induction of cell signaling by IL-4 involves interaction with its cognate receptors, a complex of IL-4Ralpha with either the common gamma-chain or the IL-13R chain alpha1 (IL-13Ralpha1). We found that IL-4 bound to the extracellular domain of IL-4Ralpha (soluble human (sh)IL-4Ralpha) with high affinity and specificity. In contrast with the sequential mechanism of binding and stabilization afforded by IL-4Ralpha to the binding of IL-13 to IL-13Ralpha1, neither common gamma-chain nor IL-13Ralpha1 contributed significantly to the stabilization of the IL-4:IL-4Ralpha complex. Based on the different mechanisms of binding and stabilization of the IL-4R and IL-13R complexes, we compared the effects of shIL-4Ralpha and an IL-4 double mutein (R121D/Y124D, IL-4R antagonist) on IL-4- and IL-13-mediated responses. Whereas IL-4R antagonist blocked responses to both cytokines, shIL-4Ralpha only blocked IL-4. However, shIL-4Ralpha stabilized and augmented IL-13-mediated STAT6 activation and eotaxin production by primary human bronchial fibroblasts at suboptimal doses of IL-13. These data demonstrate that IL-4Ralpha plays a key role in the binding affinity of both IL-13R and IL-4R complexes. Under certain conditions, shIL-4Ralpha has the potential to stabilize binding IL-13 to its receptor to augment IL-13-mediated responses. Thus, complete understanding of the binding interactions between IL-4 and IL-13 and their cognate receptors may facilitate development of novel treatments for asthma that selectively target these cytokines without unpredicted or detrimental side effects.

Expression and targeting of interleukin-4 receptor for primary and advanced ovarian cancer therapy

Because the most characteristic property of ovarian cancer is i.p. spread, the majority of patients are diagnosed at an advanced stage, leading to limited availability of options for curative therapies. With an intent to identify targeted therapeutic approaches, we have observed that approximately 60% of 21 ovarian cancer tissue samples express a high density of interleukin-4 receptor (IL-4R), whereas normal ovarian tissues tested (n = 7) expressed no or low levels of IL-4R. To target IL-4R, we have developed IL-4 cytotoxin, in which circular-permuted IL-4 is fused to a mutated form of Pseudomonas exotoxin. This cytotoxin is specifically and highly cytotoxic to PA-1, IGROV-1, and SK-OV3 ovarian carcinoma cell lines in vitro. In addition, it shows remarkable antitumor activities against established s.c. ovarian tumors in immunodeficient animals. i.p. administration of IL-4 cytotoxin in mice with orthotopically implanted ovarian tumors caused regression of established tumors and prevented these animals from tumor metastasis. Continuous i.p. infusion of IL-4 cytotoxin prolonged survival of tumor-bearing mice even with bulky disease. These results indicate that IL-4R-targeted cytotoxin may be a useful agent for the management of patients with ovarian cancer, and further studies need to be done to evaluate its safety, tolerability, and efficacy.

IL-4 is more effective than IL-13 for in vitro differentiation of dendritic cells from peripheral blood mononuclear cells

Dendritic cells (DCs) are the most potent professional antigen-presenting cells which can activate T cells to induce the primary immune response. For clinical studies, DCs are often differentiated in vitro from peripheral blood mononuclear cells (PBMCs) through treatment with granulocyte macrophage colony-stimulating factor (GM-CSF) and IL-4. However, IL-13, a cytokine closely related to IL-4, has also been reported to induce differentiation equally or more efficiently when used with GM-CSF. For the present study, we compared the DC characteristics exhibited by iDCs and LPS-matured DCs differentiated from PBMCs using GM-CSF and IL-4 or IL-13. Physical characteristics examined include cellular morphology and surface phenotype. Functional traits investigated include FITC-dextran uptake, IL-10 and IL-12 production, allostimulation and cytokine production by stimulated T cells and antigen-specific T cell stimulation. Compared with IL-13-derived DCs, IL-4 treatment yielded more differentiated DCs, with extensive dendrites and higher expression of DC-SIGN, DEC-205, CD86 and HLA-DR. In addition, IL-4 DCs were more efficient at inducing allogeneic T cell proliferation and immature IL-4 DCs had higher endocytic activity at low FITC-dextran concentrations (1 microg ml(-1)). Although IL-13 was capable of generating DCs from PBMCs, it was not as effective as IL-4 in generating DC phenotype and functionality. Thus, the use of GM-CSF and IL-4 is the more efficient treatment for inducing DC differentiation from PBMCs.

IL-13 R130Q, a common variant associated with allergy and asthma, enhances effector mechanisms essential for human allergic inflammation

Genetic factors are known to strongly influence susceptibility to allergic inflammation. The Th2 cytokine IL-13 is a central mediator of allergy and asthma, and common single-nucleotide polymorphisms in IL13 are associated with allergic phenotypes in several ethnically diverse populations. In particular, IL13+2044GA is expected to result in the nonconservative replacement of arginine 130 (R130) with glutamine (Q). We examined the impact of IL13+2044GA on the functional properties of IL-13 by directly comparing the activity of WT IL-13 and IL-13 R130Q on primary human cells involved in the effector mechanisms of allergic inflammation. Our results show that IL-13 R130Q was significantly more active than WT IL-13 in inducing STAT6 phosphorylation and CD23 expression in monocytes and hydrocortisone-dependent IgE switching in B cells. Notably, IL-13 R130Q was neutralized less effectively than WT IL-13 by an IL-13R2 decoy. Decreased neutralization of the minor variant could contribute to its enhanced in vivo activity. Neither IL-13 variant was able to engage T cells, which suggests that increased allergic inflammation in carriers of IL13+2044A depends on enhanced IL-13-mediated Th2 effector functions rather than increased Th2 differentiation. Collectively, our data indicate that natural variation in the coding region of IL13 may be an important genetic determinant of susceptibility to allergy.

Autoregulation of CCL26 synthesis and secretion in A549 cells: a possible mechanism by which alveolar epithelial cells modulate airway inflammation

Eotaxins (CCL11, CCL24, CCL26) originating from airway epithelial cells and leukocytes have been detected in bronchoalveolar lavage of asthmatics. Although the alveolar epithelium is the destination of uncleared allergens and other inflammatory products, scanty information exists on their contribution to the generation and regulation of the eotaxins. We envisioned a state whereby alveolar type II cells, a known source of other inflammatory proteins, could be involved in both the production and regulation of CCL24 and CCL26. Herein, we demonstrated that all three eotaxins are constitutively expressed in A549 cells. IL-4 and IL-13 stimulated a concentration-dependent secretion of CCL24 and CCL26. The cytokines did not act synergistically. Cycloheximide and actinomycin D abrogated IL-4- and IL-13-dependent CCL26 but not CCL24 secretion. Both IL-13 and IL-4 stimulated CCL26 synthesis that was inhibited in a concentration-dependent manner by CCL26 but not CCL24. Only CCL26 reduced expression of CCR3 receptors by 30-40%. On the other hand, anti-CCR3 pretreatment reduced IL-4+IL-13-dependent CCL26 secretion, implying autoregulation. A CCR3-specific antagonist (SB-328437) significantly decreased IL-4-dependent synthesis and release of CCL26. Eosinophils treated with medium from IL-4-stimulated A549 cells preincubated with anti-CCL26 showed a marked decrease of superoxide anion production compared with anti-CCL24 treated. These results suggest that CCL26 is a major eotaxin synthesized and released by alveolar epithelial cells and is involved in autoregulation of CCR3 receptors and other eotaxins. This CCL26-CCR3 ligand-receptor system may be an attractive target for development of therapeutics that limits progress of inflammation in airway disease.