Interleukin-13 Receptor α1-Mediated Signaling Regulates Age-Associated/Autoimmune B Cell Expansion and Lupus Pathogenesis

OBJECTIVE

Age-associated/autoimmune B cells (ABCs) are an emerging B cell subset with aberrant expansion in systemic lupus erythematosus. ABC generation and differentiation exhibit marked sexual dimorphism, and Toll-like receptor 7 (TLR-7) engagement is a key contributor to these sex differences. ABC generation is also controlled by interleukin-21 (IL-21) and its interplay with interferon-γ and IL-4. This study was undertaken to investigate whether IL-13 receptor α1 (IL-13Rα1), an X-linked receptor that transmits IL-4/IL-13 signals, regulates ABCs and lupus pathogenesis.

METHODS

Mice lacking DEF-6 and switch-associated protein 70 (double-knockout [DKO]), which preferentially develop lupus in females, were crossed with IL-13Rα1-knockout mice. IL-13Rα1-knockout male mice were also crossed with Y chromosome autoimmune accelerator (Yaa) DKO mice, which overexpress TLR-7 and develop severe disease. ABCs were assessed using flow cytometry and RNA-Seq. Lupus pathogenesis was evaluated using serologic and histologic analyses.

RESULTS

ABCs expressed higher levels of IL-13Rα1 than follicular B cells. The absence of IL-13Rα1 in either DKO female mice or Yaa DKO male mice decreased the accumulation of ABCs, the differentiation of ABCs into plasmablasts, and autoantibody production. Lack of IL-13Rα1 also prolonged survival and delayed the development of tissue inflammation. IL-13Rα1 deficiency diminished in vitro generation of ABCs, an effect that, surprisingly, could be observed in response to IL-21 alone. RNA-Seq revealed that ABCs lacking IL-13Rα1 down-regulated some histologic characteristics of B cells but up-regulated myeloid markers and proinflammatory mediators.

CONCLUSION

Our findings indicate a novel role for IL-13Rα1 in controlling ABC generation and differentiation, suggesting that IL-13Rα1 contributes to these effects by regulating a subset of IL-21-mediated signaling events. These results also suggest that X-linked genes besides TLR7 participate in the regulation of ABCs in lupus.

Loss of Interleukin-13-Receptor-Alpha-1 Induces Apoptosis and Promotes EMT in Pancreatic Cancer

In search of new therapies for pancreatic cancer, cytokine pathways have attracted increasing interest in recent years. Cytokines play a vital role in the crosstalk between tumour cells and the tumour microenvironment. The related inflammatory cytokines IL-4 and IL-13 can regularly be detected at increased levels in the microenvironment of pancreatic cancer. They share a receptor heterodimer consisting of IL-4Rα and IL-13Rα1. While IL-4Rα induces a more oncogenic phenotype, the role of IL-13Rα1 was yet to be determined. ShRNA-based knockdown of IL-13Rα1 was performed in Capan-1 and MIA PaCa-2. We assessed cell growth and migratory capacities under the influence of IL-13Rα1. Pathway alterations were detected by immunoblot analysis. We now have demonstrated that the loss of IL-13Rα1 induces apoptosis in pancreatic cancer cells. This was associated with an epithelial-to-mesenchymal transition. Loss of IL-13Rα1 also abolished the effects of exogenous IL-4 and IL-13 stimulation. Interestingly, in wild type cells, cytokine stimulation caused a similar increase in migratory capacities as after IL-13Rα1 knockdown. Overall, our results indicate the vital role of IL-13Rα1 in the progression of pancreatic cancer. The differential expression of IL-4Rα and IL-13Rα1 has to be taken into account when considering a cytokine-targeted therapy in pancreatic cancer.

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.

Soluble interleukin-13rα1: a circulating regulator of glucose

Soluble IL-13 receptor-α1, or sIL13rα1, is a soluble protein that binds to interleukin-13 (IL-13) that has been previously described in mice. The function of sIL13rα1 remains unclear, but it has been hypothesized to act as a decoy receptor for IL-13. Recent studies have identified a role for IL-13 in glucose metabolism, suggesting that a decoy receptor for IL-13 might increase circulating glucose levels. Here, we report that delivery of sIL13rα1 to mice by either gene transfer or recombinant protein decreases blood glucose levels. Surprisingly, the glucose-lowering effect of sIL13rα1 was preserved in mice lacking IL-13, demonstrating that IL-13 was not required for the effect. In contrast, deletion of IL-4 in mice eliminated the hypoglycemic effect of sIL13rα1. In humans, endogenous blood levels of IL13rα1 varied substantially, although there were no differences between diabetic and nondiabetic patients. There was no circadian variation of sIL13rα1 in normal human volunteers. Delivery of sIL13rα1 fused to a fragment crystallizable (Fc) domain provided sustained glucose lowering in mice on a high-fat diet, suggesting a potential therapeutic strategy. These data reveal sIL13rα1 as a circulating human protein with an unexpected role in glucose metabolism.

New Role for Interleukin-13 Receptor α1 in Myocardial Homeostasis and Heart Failure

BACKGROUND

The immune system plays a pivotal role in myocardial homeostasis and response to injury. Interleukins-4 and -13 are anti-inflammatory type-2 cytokines, signaling via the common interleukin-13 receptor α1 chain and the type-2 interleukin-4 receptor. The role of interleukin-13 receptor α1 in the heart is unknown.

METHODS AND RESULTS

We analyzed myocardial samples from human donors (n=136) and patients with end-stage heart failure (n=177). We found that the interleukin-13 receptor α1 is present in the myocardium and, together with the complementary type-2 interleukin-4 receptor chain Il4ra, is significantly downregulated in the hearts of patients with heart failure. Next, we showed that Il13ra1-deficient mice develop severe myocardial dysfunction and dyssynchrony compared to wild-type mice (left ventricular ejection fraction 29.7±9.9 versus 45.0±8.0; P=0.004, left ventricular end-diastolic diameter 4.2±0.2 versus 3.92±0.3; P=0.03). A bioinformatic analysis of mouse hearts indicated that interleukin-13 receptor α1 regulates critical pathways in the heart other than the immune system, such as extracellular matrix (normalized enrichment score=1.90; false discovery rate q=0.005) and glucose metabolism (normalized enrichment score=-2.36; false discovery rate q=0). Deficiency of Il13ra1 was associated with reduced collagen deposition under normal and pressure-overload conditions.

CONCLUSIONS

The results of our studies in humans and mice indicate, for the first time, a role of interleukin-13 receptor α1 in myocardial homeostasis and heart failure and suggests a new therapeutic target to treat heart disease.

IL-4 mRNA Is Downregulated in the Liver of Pancreatic Cancer Patients Suffering from Cachexia

BACKGROUND

Interleukin-4 (IL-4) together with interleukin-13 (IL-13) play an important role in inflammation and wound repair, and are known to be upregulated in human skeletal muscle after strenuous physical exercise. Additionally, these cytokines may act as autocrine growth factors in pancreatic cancer cells. We hypothesize that IL-4, IL-13, and their corresponding receptors are involved in mechanism of cancer cachexia.

METHODS

Tissue samples from human skeletal muscle, white fat, liver, healthy pancreas, and pancreatic ductal adenocarcinoma were analyzed by quantitative real-time polymerase chain reaction for mRNA expression levels of IL-4, IL-13, IL-4 receptor α, and IL-13 receptor α1.

RESULTS

We demonstrate for the first time that liver IL-4 mRNA is downregulated in vivo in patients with pancreatic cancer and cachexia. Additionally, IL-4 mRNA in the liver inversely correlated with musculus psoas thickness.

CONCLUSION

We speculate that suppression of IL-4 is involved in cancer cachexia, although the exact mechanisms have to be further elucidated.

IL-13 but not IL-4 signaling via IL-4Rα protects mice from papilloma formation during DMBA/TPA two-step skin carcinogenesis

Interleukin 4 (IL-4) was shown to be tumor-promoting in full carcinogenesis studies using 3-methylcholanthrene (MCA). Because heretofore the role of IL-4 in DMBA/TPA (9,10-dimethyl-1,2-benz-anthracene/12-O-tetradecanoylphorbol-13-acetate) two-stage carcinogenesis was not studied, we performed such experiments using either IL-4(-/-) or IL-4Rα(-/-) mice. We found that IL-4Rα(-/-) but not IL-4(-/-) mice have enhanced papilloma formation, suggesting that IL-13 may be involved. Indeed, IL-13(-/-) mice developed more papillomas after exposure to DMBA/TPA than their heterozygous IL-13-competent littermate controls. However, when tested in a full carcinogenesis experiment, exposure of mice to 25 μg of MCA, both IL-13(-/-) and IL-13(+/-) mice led to the same incidence of tumors. While IL-4 enhances MCA carcinogenesis, it does not play a measurable role in our DMBA/TPA carcinogenesis experiments. Conversely, IL-13 does not affect MCA carcinogenesis but protects mice from DMBA/TPA carcinogenesis. One possible explanation is that IL-4 and IL-13, although they share a common IL-4Rα chain, regulate signaling in target cells differently by employing distinct JAK/STAT-mediated signaling pathways downstream of IL-13 or IL-4 receptor complexes, resulting in different inflammatory transcriptional programs. Taken together, our results indicate that the course of DMBA/TPA- and MCA-induced carcinogenesis is affected differently by IL-4 versus IL-13-mediated inflammatory cascades.

Aglycosylated antibodies and antibody fragments produced in a scalable in vitro transcription-translation system

We describe protein synthesis, folding and assembly of antibody fragments and full-length aglycosylated antibodies using an Escherichia coli-based open cell-free synthesis (OCFS) system. We use DNA template design and high throughput screening at microliter scale to rapidly optimize production of single-chain Fv (scFv) and Fab antibody fragments that bind to human IL-23 and IL-13α1R, respectively. In addition we demonstrate production of aglycosylated immunoglobulin G (IgG 1) trastuzumab. These antibodies are produced rapidly over several hours in batch mode in standard bioreactors with linear scalable yields of hundreds of milligrams/L over a 1 million-fold change in scales up to pilot scale production. We demonstrate protein expression optimization of translation initiation region (TIR) libraries from gene synthesized linear DNA templates, optimization of the temporal assembly of a Fab from independent heavy chain and light chain plasmids and optimized expression of fully assembled trastuzumab that is equivalent to mammalian expressed material in biophysical and affinity based assays. These results illustrate how the open nature of the cell-free system can be used as a seamless antibody engineering platform from discovery to preclinical development of aglycosylated monoclonal antibodies and antibody fragments as potential therapeutics.

IL-13Rα1 expression on β-cell-specific T cells in NOD mice

OBJECTIVE

Immunotherapy using peptides from the β-cell antigen GAD65 can preserve glucose homeostasis in diabetes-prone NOD mice; however, the precise mechanisms that arrest islet-reactive T cells remain unresolved. Our previous work revealed that a dominant GAD65 epitope contained two overlapping I-A(g7)-restricted determinants, 524-538 and 530-543, with the former associated with amelioration of hyperglycemia. Here, we sought to discover whether p524-538-specific T cells could directly regulate islet-reactive T cells.

RESEARCH DESIGN AND METHODS

Prediabetic NOD mice were used to determine the relationship between peptide p524-538-induced interleukin (IL)-13 and regulation of islet autoimmunity. Pancreatic lymph node (PLN) cells from mice at distinct stages of islet inflammation, peri-insulitis versus invasive insulitis, were harvested to establish the expression pattern of IL-13 receptor α1 (IL-13Rα1) on islet-associated T cells.

RESULTS

Peptide p524-538 preferentially induced IL-13-producing T cells that antagonized the release of γ-interferon by spontaneously arising GAD65 autoimmunity, and recombinant human IL-13 inhibited proliferation of islet-reactive clonotypic T cells. A subset of CD4(+) T cells in NOD and NOD.BDC2.5 T cell receptor transgenic mice expressed functional IL-13Rα1, which induced phosphorylation of signal transducer and activator of transcription 6 in the presence of cognate cytokine. Notably, the number of IL-13Rα1(+) T cells was heightened in the PLN of young NOD mice when compared with older female counterparts with advanced insulitis. Immunization with p524-538 preserved IL-13Rα1 expression on PLN T cells.

CONCLUSIONS

IL-13 may be important for regulating autoimmunity in the early stages of insulitis, and the loss of IL-13Rα1 on islet-reactive T cells may be a biomarker for fading regional immune regulation and progression to overt diabetes.

[Effects of IL-13 and alcohol on collagen expression of human lung fibrolasts]

AIM

To investigate the effect of alcohol and/or IL-13 on the expression of collagen type I alpha 1 chain gene (COL1A1, COL3A1) mRNA and collagen production of human lung fibroblast(HFL-1).

METHODS

HFL-1 was cultured and real time RT-PCR was used to determine the expression of IL-13 receptor (IL-13Rα1, IL-13Rα2, IL-4Rα) mRNA, COL1A1 mRNA and COL3A1 mRNA. ELISA was used to determine the production of collagen type I.

RESULTS

Low level of Alcohol (25, 50, 100, 200 mmol/L) greatly up-regulated the expression of IL-13Rα1 mRNA and IL-4Rα mRNA of HFL-1, but IL-13Rα2 mRNA expression was decreased. low level of alcohol (25, 50, 100, 200 mmol/L) had no effect on the expression of COL1A1 and COL3A1. IL-13 (10, 20, 50 μg/L) stimulated the expression of COL1A1 and COL3A1 in a dose-dependent manner. The expression of COL1A1 and COL3A1 induced by combination of alcohol (200 mmol/L) and IL-13(10 μg/L, 20 μg/L, 50 μg/L) was significantly higher than IL-13(10, 20, 50 μg/L) alone. Combination of alcohol (200 mmol/L) and IL-13(10, 20, 50 μg/L) could significantly increase collagen typeI production than IL-13(10, 20, 50 μg/L) alone.

CONCLUSION

Low level of alcohol has no effect on the mRNA expression of COL1A1 and COL3A1 of HFL-1cells, but has great effect on the mRNA expression of IL-13Rα1, IL-13Rα2 and IL-4Rα. Combination of alcohol and IL-13 significantly up-regulated the collagen production and expression of COL1A1 and COL3A1 of HFL-1 cells.

Regulation of IL-13 receptor α1 expression and signaling on human tonsillar B-lymphocyte subsets

BACKGROUND

T(H)2 cytokines play crucial roles in driving human B lymphocytes to produce IgE. However, it is unclear whether IL-4 and IL-13 have parallel or sequential roles in the development of B lymphocytes.

OBJECTIVE

We investigated IL-13 receptor (IL-13R) expression and regulation in mature and immature human B cells.

METHODS

Purified B cells were isolated from human tonsils. We evaluated IL-13Ralpha1 mRNA expression using real-time PCR and IL-13Ralpha1 and IL-4 receptor (IL-4R) alpha expression using flow cytometry and microscopy. Signal transduction was assessed on the basis of signal transducer and activator of transcription 6 phosphorylation.

RESULTS

IL13Ralpha1 mRNA was induced after stimulation with anti-CD40 antibodies, anti-CD40 plus IL-4, or anti-IgM/IgG. Baseline surface IL13Ralpha1 levels were low in unstimulated B cells but increased significantly at 24 hours and were sustained for 5 to 14 days. In contrast, IL4R alpha was constitutively expressed on tonsillar B cells, and levels did not significantly vary after stimulation. B cells activated by CD40 ligation or B-cell receptor cross-linking, but not resting B cells, showed significant increases in signal transducer and activator of transcription 6 phosphorylation in response to IL-13. IL-13Ralpha1 expression was induced on mature and memory B cells, as well as on naive subsets.

CONCLUSIONS

There is lower constitutive expression and signaling of IL13Ralpha1 in resting tonsillar B lymphocytes compared with that of IL4R alpha. IL-13 is induced on both immature and mature B lymphocytes.

CLINICAL IMPLICATIONS

This implies different roles for IL-4 and IL-13 in B-cell development, which would allow for specific targeting of IL-13 in IgE-mediated diseases.

Rat gene mapping in the post-genome sequencing era: the continued utility of cell hybrids to localize rat genes (Cks2, Ephb4, Fabp5, Il13ra1, Rpl10, Ssr4)

Finding the position of a gene is now easily done when the genome sequence is available: the gene position is generally found by a simple query of genomic databases such as those available at the Ensembl browser or the NCBI. We were interested in determining the position of 125 cancer-related rat genes and we found that the position of most of these genes (110) could indeed be identified in this manner. However, in 15 cases, the gene position was not available in these databases, or the results were ambiguous. We then explored a more specialized database, namely the Rat Genome Database, and experimentally mapped these genes using standard and radiation cell hybrids. The 15 genes in question could be localized unambiguously. In four cases, the radiation cell hybrids were indispensable: the sequence of these four genes could not be found in the rat genome sequence. On the basis of the sample we examined, it thus appears that a classical gene mapping method is still required to localize about 3% of the rat genes, as if 3% of the rat gene sequences were lacking in the current rat genome sequence.

Genetic association studies of interleukin-13 receptor alpha1 subunit gene polymorphisms in asthma and atopy

Interleukin (IL)-13 plays a central role in asthma pathogenesis by binding to the IL-13 receptor, which is a heterodimer composed of the IL-13 receptor alpha1 subunit (IL-13Ralpha1) and IL-4Ralpha. The genetic diversity at the IL-13Ralpha1 gene (IL13RA1) locus on chromosome Xq24 was characterised and the association of identified polymorphisms with asthma and atopy phenotypes examined. The promoter and coding region of IL13RA1 were screened for common genetic variants, and polymorphisms found were genotyped in a large cohort of 341 asthmatic Caucasian families (each containing at least two asthmatic siblings) and 182 nonasthmatic control subjects. Genetic association was determined using case-control and transmission disequilibrium test analyses. Two common polymorphisms were identified, a newly found thymidine (T) to guanine (G) transition of nucleotide -281 (-281T>G) single nucleotide polymorphism in the IL13RA1 promoter and the previously described 1365A>G variant in the IL13RA1 proximal 3' untranslated region. No significant association of either -281T>G or 1365A>G with risk of asthma or atopy phenotypes was found, apart from a suggestive association between the IL13RA1 -281T/1365A haplotype and raised total serum immunoglobulin E levels in adult female asthmatics. These findings indicate that the interleukin-13 receptor alpha1 subunit gene -281T>G and 1365A>G polymorphisms do not contribute to asthma susceptibility or severity, although the interleukin-13 receptor alpha1 subunit gene locus might be involved in the control of immunoglobulin E production.

Expression and structure of interleukin 4 receptor (IL-4R) complex in human invasive pituitary adenomas

Pituitary adenomas are frequently invasive of surrounding tissues, which adversely affects the surgical outcome and the disease-free survival of patients. In the present study, Interleukin 4 receptor (IL-4R) complex has been investigated to figure out whether the three subunits are overexpressed in human invasive pituitary adenomas. Reverse transcription-polymerase chain reaction (RT-PCR) analysis for interleukin 4 receptor alpha (IL-4Ralpha), interleukin 13 receptor alpha1 (IL-13Ralpha1), interleukin 2 receptor gammac (IL-2Rgammac) were performed on total RNA extracted from 10 non-invasive pituitary adenomas, 30 invasive pituitary adenomas, one glioblastoma multiforme, one normal human pituitary tissue sample and one normal human brain tissue sample. Quantitative real-time PCR and in situ immunofluorescence assay were performed in five invasive functioning pituitary adenoma samples and five invasive nonfunctioning pituitary adenoma samples. RT-PCR analysis for IL-4Ralpha, IL-13Ralpha1 and IL-2Rgammac chains were overexpressed in invasive pituitary adenomas. The transcripts for three subunits were not/weakly expressed in normal pituitary tissue and normal brain tissue. The quantitative real-time PCR and in situ immunofluorescence assay confirmed the results of the RT-PCR analysis. Our results indicate that human invasive pituitary adenomas express type III IL-4R complex. These receptors may serve as a novel target for immunotoxin therapy in patients with invasive pituitary adenomas who are not amenable to total surgical resection or for recurrent cases.

Skeletal muscle IL-4, IL-4Ralpha, IL-13 and IL-13Ralpha1 expression and response to strength training

Interleukin-4 (IL-4) and interleukin-13 (IL-13) are Th2 cytokines involved in various immune responses and only a few reports examine skeletal muscle and the possible role of Th2 cytokines in myoblast fusion and myotube maturation. We hypothesized that IL-4, IL-13 and their receptors are involved in skeletal muscle adaptations to strength training. We investigated the effects of 6 weeks of strength training with different muscle load on IL-4, IL-13, IL-4Ralpha and IL-13Ralpha1 expression in skeletal muscle: training with maximal contractions (Max group, n = 12) and training with lower load combined with ballistic and stretch-shortening contractions (Combi group, n = 12). Muscle samples were taken from triceps brachii before and after the 6 weeks of training. mRNA levels of IL-4, IL-13, IL-4Ralpha and IL-13Ralpha1 expression were determined by real-time PCR and IL-4 protein expression by ELISA. We demonstrate for the first time that IL-4, IL-13, IL-4Ralpha and IL-13Ralpha1 are expressed in skeletal muscle in vivo and are up-regulated after strength training. Higher training load in Max leads to higher cytokine responses, which was significant for IL-4Ralpha though IL-4 protein expression did not change significantly. Although the exact mechanisms have yet to be established, and these results may be preliminary, we speculate that IL-4, IL-13, IL-4Ralpha and IL-13Ralpha1 are involved in muscle hypertrophy, MHC-transformation and anti-inflammatory damage control that occur during strength training.

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.

IL13RA2 gene polymorphisms are associated with systemic sclerosis

OBJECTIVE

To investigate the influence of genetic variability on the phenotypic expression of systemic sclerosis (SSc), by testing possible associations between single nucleotide polymorphisms (SNP) in IL13RA1 and IL13RA2 genes and SSc in a Caucasian population.

METHODS

As IL13RA1 and IL13RA2 are located on the X chromosome and SSc occurs far more frequently in women than in men, only women were genotyped. The study group comprised 97 women with SSc, 36 with diffuse (dcSSc) and 61 with limited (lcSSc) cutaneous forms of disease, and 109 healthy controls. Patients and controls were Caucasian. We investigated 4 SNP in IL13RA1 and 3 in IL13RA2 by polymerase chain reaction amplifications and enzymatic digestion or primer extension reactions and denaturing high-performance liquid chromatography.

RESULTS

We detected an association between IL13RA2 rs638376 and patients with SSc [p = 0.004, odds ratio (OR) = 1.85, confidence interval (CI) 1.22-2.74, p corr = 0.02], as well as with dcSSc in that subgroup of patients (p = 0.01, OR 2.22, 95% CI 1.27-3.89, p corr = 0.05). The IL13RA2 rs638376G allele frequency was higher in patients with SSc (51.6%) than in controls (36.4%, p = 0.003, OR 1.86, 95% CI 1.24-2.79, p corr = 0.015) and in the subgroup with dcSSc (57.6%) than in controls (36.4%, p = 0.003, OR 2.37, 95% CI 1.35-4.15, p corr = 0.015). One other IL13RA2 SNP was only associated with the dcSSc subgroup: the IL13RA2 rs5946040G allele was more common in patients with dcSSc (33.8%) than in controls (17%, p = 0.004, OR 2.5, 95% CI 1.36-4.60, p corr = 0.02).

CONCLUSION

Our data suggest that IL13RA2 gene polymorphisms may be involved in susceptibility to SSc. Further studies are under way to show that they contribute to disease.

Gene-gene interaction between IL-13 and IL-13Ralpha1 is associated with total IgE in Korean children with atopic asthma

Interleukin (IL)-13, which is essential for IgE synthesis, mediates its effects by binding with a receptor composed of IL-4Ralpha and IL-13Ralpha1. We investigated the effects of IL-13 and IL-13Ralpha1 polymorphisms in Korean children with asthma, and whether these have been associated with IgE production. We enrolled 358 atopic asthmatic, 111 non-atopic asthmatic, and 146 non-atopic healthy children. IL-13 and IL-13Ralpha1 genotypes were identified using the PCR-RFLP method. There was an association between the asthma susceptibility and homozygosity for risk allele of IL-13 G+2044A. In children with atopic asthma, risk alleles in IL-13 (A-1512C and C-1112T) and IL-13Ralpha1 (A+1398G) showed increased total IgE (P=0.012, 0.015 and 0.017, respectively). Three-loci haplotype analysis for IL-13 showed that the haplotype composed of -1512C, -1112T and +2044A was associated with higher total IgE than other tested haplotypes in children with atopic asthma (P=0.003). The gene-gene interaction between risk alleles of each IL-13 promoter polymorphism and IL-13Ralpha1 polymorphism was associated with higher total IgE in children with atopic asthma (P=0.002, 0.010). These findings indicate that the IL-13 G+2044A is associated with asthma development and the IL-13 and IL-13Ralpha1 polymorphisms may interact to enhance IgE production.

Mast cells express IL-13R alpha 1: IL-13 promotes human lung mast cell proliferation and Fc epsilon RI expression

BACKGROUND

The Th2 cytokine interleukin (IL)-13 is implicated in the development of various allergic diseases including asthma. The IL-13 receptor, IL-13Ralpha1, is expressed on most leukocytes, except T-cells. Evidence to support IL-13Ralpha1 expression on mast cells is limited.

METHODS

We investigated: (i) IL-13Ralpha1 expression by human lung mast cells (HLMC); (ii) the number of IL-13Ralpha1+ bronchial submucosal mast cells in subjects with asthma and normal controls and (iii) the effect of IL-13 priming on HLMC expression of high-affinity IgE receptor (FcepsilonRI), stem cell factor receptor (CD117), histamine release, proliferation, and survival.

RESULTS

Human lung mast cell expressed IL-13Ralpha1 mRNA. IL-13Ralpha1 was highly expressed on the surface HLMC (82+/-9%). Bronchial submucosal mast cell IL-13Ralpha1 expression was higher in asthmatics (86+/-2%) than normal controls (78+/-2%; P=0.015). IL-13 priming for 30 min did not increase HLMC histamine release, in the presence or absence of SCF or in response to IgE/anti-IgE activation. IL-13 priming for 5 days upregulated HLMC FcepsilonRI expression (22% increase in fluorescent intensity; P=0.003), increased histamine release following IgE/anti-IgE activation by 56% (P=0.03) and increased proliferation by 50% (P=0.003) without affecting cell survival or CD117 expression. The IL-13 specific neutralizing antibody CAT-354 inhibited all IL-13 mediated effects.

CONCLUSION

Human lung mast cell express IL-13Ralpha1 and activation by IL-13 for 5 days increased FcepsilonRI expression and proliferation. Histamine release was not affected by short-term priming with IL-13, but was upregulated by priming for 5 days suggesting that this effect was mediated by the increased FcepsilonRI expression. These data support the view that targeting IL-13 may be beneficial in the treatment of asthma.