IL-4 and IL-13 receptors: are they one and the same?

Non-coding RNA-based regulation of inflammation

Inflammation is a multifactorial process and various biological mechanisms and pathways participate in its development. The presence of inflammation is involved in pathogenesis of different diseases such as diabetes mellitus, cardiovascular diseases and even, cancer. Non-coding RNAs (ncRNAs) comprise large part of transcribed genome and their critical function in physiological and pathological conditions has been confirmed. The present review focuses on miRNAs, lncRNAs and circRNAs as ncRNAs and their potential functions in inflammation regulation and resolution. Pro-inflammatory and anti-inflammatory factors are regulated by miRNAs via binding to 3'-UTR or indirectly via affecting other pathways such as SIRT1 and NF-κB. LncRNAs display a similar function and they can also affect miRNAs via sponging in regulating levels of cytokines. CircRNAs mainly affect miRNAs and reduce their expression in regulating cytokine levels. Notably, exosomal ncRNAs have shown capacity in inflammation resolution. In addition to pre-clinical studies, clinical trials have examined role of ncRNAs in inflammation-mediated disease pathogenesis and cytokine regulation. The therapeutic targeting of ncRNAs using drugs and nucleic acids have been analyzed to reduce inflammation in disease therapy. Therefore, ncRNAs can serve as diagnostic, prognostic and therapeutic targets in inflammation-related diseases in pre-clinical and clinical backgrounds.

Investigation of Active Anti-Inflammatory Constituents of Essential Oil from Pinus koraiensis (Sieb. et Zucc.) Wood in LPS-Stimulated RBL-2H3 Cells

In a previous study, we demonstrated the anti-inflammatory activity of the essential oil extracted from Korean pine (Pinus koraiensis, Sieb. et Zucc.) wood. This study aims to investigate the active anti-inflammatory constituents of P. koraiensis oil. The essential oil was extracted from P. koraiensis wood by hydrodistillation and was divided into six fractions (A-F) through fractional distillation. Then, the anti-inflammatory activities of the fractions (A-F) were determined. Fractions A and F markedly downregulated the production of pro-inflammatory cytokines as well as the secretion of β-hexosaminidase in lipopolysaccharide (LPS)-stimulated RBL-2H3 cells. The main constituents of the active anti-inflammatory A and F fractions were (+)-α-pinene, (-)-β-pinene, (+)-α-terpineol, 3-carene, (+)-limonene, and longifolene. These six single compounds decreased the expression of inflammatory-related genes (i.e., IL-4 and IL-13) as well as the secretion of β-hexosaminidase in LPS-stimulated RBL-2H3 cells. (+)-α-Pinene, (-)-β-pinene, (+)-α-terpineol, and longifolene exhibited the strongest effects; these effects were comparable to those of the positive control (i.e., dexamethasone). The findings indicate that the interactions between these components exhibit potential for the management and/or treatment of inflammatory conditions as well as base structures for the development of novel anti-inflammatory drugs.

Immune activation during Paenibacillus brain infection in African infants with frequent cytomegalovirus co-infection

Inflammation during neonatal brain infections leads to significant secondary sequelae such as hydrocephalus, which often follows neonatal sepsis in the developing world. In 100 African hydrocephalic infants we identified the biological pathways that account for this response. The dominant bacterial pathogen was a Paenibacillus species, with frequent cytomegalovirus co-infection. A proteogenomic strategy was employed to confirm host immune response to Paenibacillus and to define the interplay within the host immune response network. Immune activation emphasized neuroinflammation, oxidative stress reaction, and extracellular matrix organization. The innate immune system response included neutrophil activity, signaling via IL-4, IL-12, IL-13, interferon, and Jak/STAT pathways. Platelet-activating factors and factors involved with microbe recognition such as Class I MHC antigen-presenting complex were also increased. Evidence suggests that dysregulated neuroinflammation propagates inflammatory hydrocephalus, and these pathways are potential targets for adjunctive treatments to reduce the hazards of neuroinflammation and risk of hydrocephalus following neonatal sepsis.

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There is a characteristic immune response to Paenibacillus brain infection

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There is a characteristic immune response to CMV brain infection

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The matching immune response validates pathogen genomic presence

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The combined results support molecular infection causality

IL-4R alpha deficiency influences hippocampal-BDNF signaling pathway to impair reference memory

Like pro-inflammatory cytokines, the role of anti-inflammatory cytokines in both learning and memory has been investigated, revealing beneficial effects for both interleukin-4 and interleukin-13 via the common interleukin-4 receptor alpha chain complex. In this study, using the Morris water maze spatial task for cognition, we compared interleukin-4 receptor alpha- deficient mice and their ligands interleukin-4/ interleukin-13 double deficient mice, on a Balb/c background. We demonstrate that while interleukin-4/ interleukin-13 double deficient mice are significantly impaired in both learning and reference memory, interleukin-4 receptor alpha-deficiency impairs only reference memory, compared to the wild-type control mice. In order to better understand how interleukin-4 receptor alpha- deficient mice are able to learn but not remember, we investigated the BDNF/TrkB- and the ARC-signaling pathways. We show that interleukin-4 receptor alpha-deficiency disrupts activation of BDNF/TrkB- and ARC-signaling pathways during reference memory, while the pathway for spatial learning is spared.

CD200R/Foxp3-mediated signalling regulates microglial activation

The heterogeneity of microglial functions have either beneficial or detrimental roles in specific physiological or pathological environments. However, the details of what transcriptional mechanisms induce microglia to take beneficial phenotypes remain unknown. Here, we report that Foxp3 is essential for beneficial outcome of the microglial response and depends upon signalling by the immunoglobulin CD200 through its receptor (CD200R). Foxp3 expression was up-regulated in microglia activated by excitotoxicity-induced hippocampal neuroinflammation. Suppression of CD200R prevented anti-inflammatory phenotype of microglia, but over-expression of Foxp3 enhanced it. Phosphorylation of STAT6, a downstream effector of CD200R, modulated transcription of Foxp3. Finally, CD200R/Foxp3-mediated signalling enhanced hippocampal neuronal viability and conferred a degree of neuroprotection, presumably by counteracting inducible nitric oxide synthase. We conclude that enhancement of Foxp3 through CD200R could be neuroprotective by targeting the microglia.

Neuroimmunology of the Interleukins 13 and 4

The cytokines interleukin 13 and 4 share a common heterodimeric receptor and are important modulators of peripheral allergic reactions. Produced primarily by T-helper type 2 lymphocytes, they are typically considered as anti-inflammatory cytokines because they can downregulate the synthesis of T-helper type 1 pro-inflammatory cytokines. Their presence and role in the brain is only beginning to be investigated and the data collected so far shows that these molecules can be produced by microglial cells and possibly by neurons. Attention has so far been given to the possible role of these molecules in neurodegeneration. Both neuroprotective or neurotoxic effects have been proposed based on evidence that interleukin 13 and 4 can reduce inflammation by promoting the M2 microglia phenotype and contributing to the death of microglia M1 phenotype, or by potentiating the effects of oxidative stress on neurons during neuro-inflammation. Remarkably, the heterodimeric subunit IL-13Rα1 of their common receptor was recently demonstrated in dopaminergic neurons of the ventral tegmental area and the substantia nigra pars compacta, suggesting the possibility that both cytokines may affect the activity of these neurons regulating reward, mood, and motor coordination. In mice and man, the gene encoding for IL-13Rα1 is expressed on the X chromosome within the PARK12 region of susceptibility to Parkinson’s disease (PD). This, together with finding that IL-13Rα1 contributes to loss of dopaminergic neurons during inflammation, indicates the possibility that these cytokines may contribute to the etiology or the progression of PD.

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.

Thymic stromal lymphopoietin and the pathophysiology of atopic disease

Thymic stromal lymphopoietin (TSLP) is an IL-7-related cytokine expressed predominantly by barrier epithelial cells. TSLP is a potent activator of several cell types, including myeloid-derived dendritic cells, monocytes/macrophages and mast cells. Recent studies have revealed an important role for TSLP in the initiation and progression of allergic inflammatory diseases. In this review, we will discuss the role of TSLP in atopic diseases, as well as its function in immune homeostasis.

Impact of single nucleotide polymorphism in IL-4, IL-4R genes and systemic concentration of IL-4 on the incidence of glioma in Iraqi patients

Glioma is the most common and believed to be one of the most aggressive tumors of the central nervous system (CNS) in humans. Very little information is available on the etiology and pathogenesis of these tumors to date. A significant gap remains in our current understanding of the molecular pathways involved in the genesis, progression and clinical behavior of these tumors. Recently, several single nucleotide polymorphisms (SNPs) have been identified in cytokine gene sequences, particularly within the promoter region of these genes, and have been shown to be associated with the development of different types of brain tumors. The present study investigates the association of C-33T SNP in the interleukin-4 (IL-4) gene with systemic IL-4 level and the S503P SNP in the IL-4R gene with the incidence of glioma. Blood samples were collected from 100 histologically confirmed adult patients with glioma, and 30 apparently healthy individuals from the same area. DNA was extracted from each blood sample, and the IL-4 and IL-4R genes were amplified using polymerase chain reaction (PCR) with gene-specific primers. Systemic IL-4 concentration was assessed in serum samples from each participant by enzyme-linked immunosorbent assay (ELISA). We observed a negative association between the homozygous genotype (CC) of the SNP C-33T of the IL-4 gene with the incidence of glioma (OR=0.19, 95% CI=0.035-1.02), while the T allele of the SNP demonstrated a significant protective association against glioma. Similarly, the heterozygous (CT) and homozygous mutant (CC) of the SNP S503P of the IL-4R gene demonstrated a significant association with glioma development (OR=0.405, 95% CI=0.17-0.969 and OR=0.147, 95% CI=0.036-0.6 respectively), while the C allele exhibited a highly significant association with protection from glioma formation. These findings suggest that the T allele of the SNP C-33T in the IL-4 gene and the C allele of the SNP S503P in IL-4R may have a protective role against glioma development.

Case-control study of eczema in relation to IL4Rα genetic polymorphisms in Japanese women: The Kyushu Okinawa Maternal and Child Health Study

Epidemiological research on the relationship between single nucleotide polymorphisms (SNPs) in the IL4Rα gene and eczema is sparse. We investigated the associations between IL4Rα SNPs rs1805011, rs1805015 and rs1801275 and risk of eczema in young adult Japanese women. Included were 188 women who met the criteria of the International Study of Asthma and Allergies in Childhood (ISAAC) for eczema. Controls were 635 women without eczema according to the ISAAC criteria who also had not been diagnosed with asthma, atopic eczema and/or allergic rhinitis by a doctor. Adjustment was made for age, region of residence, number of children, smoking and education. Under the additive model, SNP rs1805011 was significantly related to eczema: the adjusted OR was 0.55 (95% CI: 0.31-0.99). SNP rs1805015 was significantly associated with eczema in the additive and dominant models: the adjusted ORs were 0.55 (95% CI: 0.30-0.98) and 0.55 (95% CI: 0.30-0.997), respectively. There was no significant association between SNP rs1801275 and eczema. None of the haplotypes were significantly related to eczema. Significant associations between SNPs rs1805011 and rs1805015 and eczema were reported in women who had never smoked, but not in those who had ever smoked; the multiplicative interactions, however, were not significant. This is the first study to demonstrate significant associations between IL4Rα SNPs rs1805011 and rs1805015 and eczema. We do not find evidence for interactions affecting eczema between IL4Rα SNPs and smoking.

IL-4 in the brain: a cytokine to remember

IL-4 has been extensively studied in the context of its role in immunity. Accumulating evidence indicates, however, that it also plays a critical role in higher functions of the normal brain, such as memory and learning. In this review, we summarize current knowledge of the basic immunology of IL-4, describe how and where this cytokine appears to operate in normal brain function, and propose a hypothesis concerning its potential role in neurological pathologies.

Contribution of alternatively activated macrophages to allergic lung inflammation: a tale of mice and men

The concept that macrophages play an active role in inflammatory responses began its development in the late 1800s with the now iconic studies by Elie Metchnikoff using starfish larvae and Daphnia [reviewed in Kaufmann SHE: Nat Immunol 2008;9:705-712 and Cavaillon JM: J Leukoc Biol 2011;90:413-424]. Based on his observation of the phagocyte response to a foreign body (rose thorn) and yeast, he proposed that phagocytes acted in host defense and were active participants in the inflammatory process. Flash forward more than 100 years and we find that these basic tenets hold true. However, it is now appreciated that macrophages come in many different flavors and can adopt a variety of nuanced phenotypes depending on the tissue environment in which the macrophage is found. In this brief review, we discuss the role of one type of macrophage termed the alternatively activated macrophage (AAM), also known as the M2 type of macrophage, in regulating allergic lung inflammation and asthma. Recent studies using mouse models of allergic lung inflammation and samples from human asthma patients contribute to the emerging concept that AAMs are not just bystanders of the interleukin (IL)-4- and IL-13-rich environment found in allergic asthma but are also active players in orchestrating allergic lung disease.

The polymorphisms of IL-4, IL-4R and IL-13 genes and bladder cancer risk in a Chinese population: a case-control study

Accumulating evidence suggests that inflammatory process may play a role in bladder carcinogenesis. However, the exact mechanisms of how the inflammatory factors associate with bladder cancer risk are still unknown. In this study, we explored whether polymorphisms (i.e. IL-4 C-590T, IL-4R Ile50Val, IL-4R Ser478Pro, IL-4R Gln551Arg, IL-13 C-1055T and IL-13 Arg130Gln) of IL-4, IL-4R and IL-13 genes predicted Chinese bladder cancer risk in 817 bladder cancer and 1,141 controls. Genotyping was performed by using the TaqMan method. We did not find any overall association between these single nucleotide polymorphisms (SNPs) and bladder cancer susceptibility in a Chinese population. However, in the classification and regression tree (CART) analysis, we found that carriers of IL-13 C-1055T variant genotype in smokers had a 2.57-fold increased bladder cancer risk with a 55% patient rate (OR = 2.57; 95% CI = 1.93-3.43), comparing with non-smokers. Similar result was also observed in combination of IL-13 C-1055T and IL-13 Arg130Gln in smokers. By multifactor dimensionality reduction (MDR) analysis, the best interaction model was the two-factor model that smokers with the IL-13 C-1055T genotypes were the subgroup to predict bladder cancer risk. The results suggested that the genetic variants in IL-4, IL-4R and IL-13 genes might modulate the bladder cancer risk in a Chinese population.

Fish T cells: recent advances through genomics

This brief review is intended to provide a concise overview of the current literature concerning T cells, advances in identifying distinct T cell functional subsets, and in distinguishing effector cells from memory cells. We compare and contrast a wealth of recent progress made in T cell immunology of teleost, elasmobranch, and agnathan fish, to knowledge derived from mammalian T cell studies. From genome studies, fish clearly have most components associated with T cell function and we can speculate on the presence of putative T cell subsets, and the ability to detect their differentiation to form memory cells. Some recombinant proteins for T cell associated cytokines and antibodies for T cell surface receptors have been generated that will facilitate studying the functional roles of teleost T cells during immune responses. Although there is still a long way to go, major advances have occurred in recent years for investigating T cell responses, thus phenotypic and functional characterization is on the near horizon.

Gene Therapy against Murine Melanoma B16F10-Nex2 Using IL-13Ralpha2-Fc Chimera and Interleukin 12 in Association with a Cyclopalladated Drug

Interleukin 13 (IL-13) is immunoregulatory in many diseases, including cancer. The protective or suppressive role of CD1-restricted natural killer T cells (NKT cells) in tumor immunosurveillance and immunity is well documented. Interleukin 12 (IL-12) can activate type I NKT cells to produce interferon-gamma (IFN-gamma), whereas type II NKT cells may produce IL-13. The high-affinity chain of IL-13Ralpha2 may act as negative inhibitor, suppressing the action of IL-13 and helping to maintain tumor immunosurveillance. We constructed an mIL-13Ralpha2-Fc chimera in a eukaryotic expression vector and confirmed the identity of the recombinant protein by immunoblot analysis and binding to IL-13 in chemiluminescent ELISA. Such DNA vaccine was tested against syngeneic B16F10-Nex2 murine melanoma. In vivo experiments showed a protective effect mediated by high production of IFN-gamma and down-regulation of anti-inflammatory interleukins mainly by NKT 1.1(+) T cells. Biochemoterapy in vivo with plasmid encoding mIL-13Ralpha2-Fc in association with plasmid encoding IL-12 and the 7A cyclopalladated drug led to a significant reduction in the tumor evolution with 30% tumor-free mice. We conclude that IL-12 gene therapy, followed by continuous administration of IL-13Ralpha2-Fc gene along with 7A-drug has antitumor activity involving the high production of proinflammatory cytokines and low immune suppression, specifically by NK1.1(+)T cells producing IL-13 and IL-10.

Use of biologicals as immunotherapy in asthma and related diseases

Recent advances in our understanding of the immune-mediated inflammatory pathways in asthma and other allergic diseases have resulted in the development of novel biological compounds for the treatment of these conditions. These compounds offer an advantage over glucocorticosteroid therapy by specifically targeting components of the immunologic cascade, thereby allowing patients to reduce or discontinue their glucocorticosteroid treatment. Another potential advantage of biological compounds is that they may provide additional anti-inflammatory benefits, over and above those provided by glucocorticosteroid therapy, for patients who continue to have evidence of refractory asthma. The anti-IgE monoclonal antibody omalizumab is already being used for the treatment of allergic asthma and a number of other biological therapies are currently in various stages of clinical development. The purpose of this review is to summarize the data from these studies and to provide a rationale for the use of these compounds in asthma and related allergic airway diseases.

Phosphorylation of signal transducer and activator of transcription 6 (STAT6) and STAT1, but not STAT3, induced by antigen inhalation in bronchial smooth muscles of sensitized mice

The signal transducer and activator of transcription (STAT) family of molecules play a critical role in the signaling of many cytokines. In addition to STAT6, implication of STAT1 and STAT3 in the development of airway hyperresponsiveness (AHR) has also been suggested in allergic bronchial asthma. However, there is little information whether or not antigen challenge really causes the in vivo activation of these STAT molecules in bronchial smooth muscles (BSMs). In the present study, the activations of these STATs were examined in BSMs of mice with allergic bronchial asthma. Male BALB/c mice were sensitized and repeatedly challenged with ovalbumin (OA) antigen. Total protein samples of the left main bronchi were prepared at 3 after the last OA challenge, and Western blot analyses for total and tyrosine-phosphorylated STATs molecules were conducted. In addition to the phosphorylation of STAT6, a significant increase in the level of phosphorylated STAT1 was also observed after the antigen exposure. In contrast, no significant increase in the level of phosphorylated STAT3 was observed in this mouse model of allergic bronchial asthma. The antigen exposure did not change the protein expressions of these STATs themselves. These findings suggest that STAT6 and STAT1, but not STAT3, might be crucial signal transducers in the development of BSM hyperresponsiveness, one of the causes of AHR in asthmatics.

Interleukin-4/interleukin-4 receptor gene polymorphisms in hand osteoarthritis

OBJECTIVE

IL-13/IL-4/IL-4R system has strong chondroprotective activity. We investigated polymorphisms in these genes as potential hand osteoarthritis (OA) susceptibility loci by performing a case-control association study.

METHODS

Eighteen common single nucleotide polymorphisms (SNPs) (nine in IL-4R, five in IL-4 and four in IL-13) were genotyped in 403 patients (380 females) with hand OA and 322 healthy controls (308 females).

RESULTS

Two SNPs (rs1805013 and rs1805015), mapping to the IL-4R gene, were associated with P-values of 0.0116 and 0.0305 respectively in the whole sample. As far as the non-erosive hand OA group (n=159) is concerned, the significance level of association of SNP rs1805013 is increased. After correction for multiple testing (correction for the 54 tests) the significance was not retained. None of the IL-13 SNPs analyzed showed association with hand OA. Some of the analyzed SNP within the IL-4 gene showed significant association with hand OA only when considering subgroups of patients. With respect to the CMC1 OA group, two SNPs in IL-4 (rs2243250 and rs2243274) showed association with a P-value of 0.027 and 0.018 respectively. None of these associations remained after correction for multiple testing.

CONCLUSIONS

The present study shows a trend to an association between non-erosive hand OA in Caucasian population and a genetic variant in the coding region of IL-4R gene. Our results, in keeping with previous data on hip OA, confirm the suggestion that IL-4/IL-4R system plays a role in OA pathogenesis. Further confirmation studies on different populations are necessary.

Antigen exposure causes activations of signal transducer and activator of transcription 6 (STAT6) and STAT1, but not STAT3, in lungs of sensitized mice

The signal transducer and activator of transcription (STAT) family of molecules play a critical role in the signaling of many cytokines. In addition to STAT6, implication of STAT1 and STAT3 in the pathogenesis of allergic airway diseases has also been suggested. However, there is little information whether or not antigen challenge to sensitized animals causes the in vivo activation of STAT1 and/or STAT3 in the airways. In the present study, the activations of these STAT molecules were monitored in lungs of mice with allergic bronchial asthma. Male BALB/c mice were sensitized and repeatedly challenged with ovalbumin (OA) antigen. Total protein samples of lungs were prepared at ∼1-24 h after the last OA challenge, and western blot analyses for total and tyrosine-phosphorylated STATs (pSTATs) molecules were conducted. In addition to the phosphorylation of STAT6, STAT1 was also phosphorylated in lungs after the inhalation of OA antigen. Both the phosphorylation of STAT6 and STAT1 occurred at the early stage after the antigen exposure. In contrast, no significant increase in the level of pSTAT3 was observed in this mouse model of allergic bronchial asthma. In conclusion, the current findings suggest that STAT6 and STAT1, but not STAT3, might be crucial signal transducers in the pathogenesis of allergic bronchial asthma.

Immunisation route-dependent expression of IL-4/IL-13 can modulate HIV-specific CD8(+) CTL avidity

All HIV-1 'systemic vaccine trials' in humans have yielded poor outcomes. Thus, it is important to understand whether the route of delivery influences the quality of protective CTL immunity. Using heterologous poxvirus immunisation we have shown that systemically (i.m./i.m.) immunised CD8(+) T cells generated higher levels of IL-4/IL-13 compared to mucosal delivery and expression also correlated with i.m./i.m. immunised mice eliciting CTL of lower avidity. Studies using IL-4(-/-) and IL-13(-/-) KO mice have shown that the capacity to express IFN-gamma, IL-4 and/or IL-13 by K(d)Gag(197-205)-specific CTL differed between these groups and was inversely correlated with CTL avidity (IL-13(-/-)>IL-4(-/-)>BALB/c), although no significant differences in the magnitude of CTL responses were observed between IL-13(-/-) and wild type mice. When IL-13 was reconstituted in IL-13(-/-) splenocytes in vitro, their ability to bind tetramers also decreased significantly. Our data reveal that total absence of IL-13 can greatly enhance CTL avidity. In contrast, extracellular IL-4 appears to be important in maintaining long-term Th1/Th2 balance in CTL, even though expression of IL-4 by CTL markedly reduced avidity. STAT6(-/-) mice also showed memory CTL of higher avidity. Furthermore, CCL5 expression in K(d)Gag(197-205)-specific CTL was also regulated by IL-4/IL-13.

An atopy-associated polymorphism in the ectodomain of the IL-4R(alpha) chain (V50) regulates the persistence of STAT6 phosphorylation

Several commonly occurring polymorphisms in the IL-4R(alpha) have been associated with atopy in humans; the Q576R and the S503P polymorphisms reside in the cytoplasmic domain, whereas the I50 to V50 polymorphism resides in the extracellular domain of the IL-4R(alpha). The effects of these polymorphisms on signaling remain controversial. To determine the effect of the polymorphisms on IL-4 signaling in human cells, we stably transfected the human monocytic cell line U937 with murine IL-4R(alpha) cDNA bearing the I or V at position 50 and the P503/R576 double mutant. Each form of the murine IL-4R(alpha) mediated tyrosine phosphorylation of STAT6 in response to murine IL-4 treatment similar to the induction of tyrosine phosphorylation by human IL-4 signaling through the endogenous human IL-4R(alpha). After IL-4 removal, tyrosine-phosphorylated STAT6 rapidly decayed in cells expressing I50 or P503R576 murine IL-4Ralpha. In contrast, STAT6 remained significantly phosphorylated for several hours after murine IL-4 withdrawal in cells expressing the V50 polymorphism. This persistence in tyrosine-phosphorylated STAT6 was associated with persistence in CIS mRNA expression. Blocking IL-4 signaling during the decay phase using the JAK inhibitor AG490 or the anti-IL-4R(alpha) Ab M1 abrogated the persistence of phosphorylated STAT6 observed in the V50-IL-4R(alpha)-expressing cells. These results indicate that the V50 polymorphism promotes sustained STAT6 phosphorylation and that this process is mediated by continued engagement of IL-4R(alpha), suggesting enhanced responses of V50 IL-4R when IL-4 is limiting.

Understanding respiratory syncytial virus (RSV) vaccine-enhanced disease

Respiratory syncytial virus (RSV) is the most common cause of lower respiratory tract infection in infants and children worldwide. In addition, RSV causes serious disease in elderly and immune compromised individuals. RSV infection of children previously immunized with a formalin-inactivated (FI)-RSV vaccine is associated with enhanced disease and pulmonary eosinophilia that is believed to be due to an exaggerated memory Th2 response. As a consequence, there is currently no licensed RSV vaccine and detailed studies directed towards prevention of vaccine-associated disease are a critical first step in the development of a safe and effective vaccine. The BALB/c mouse model of RSV infection faithfully mimics the human respiratory disease. Mice previously immunized with either FI-RSV or a recombinant vaccinia virus (vv) that expresses the attachment (G) glycoprotein exhibit extensive lung inflammation and injury, pulmonary eosinophilia, and enhanced disease following challenge RSV infection. CD4 T cells secreting Th2 cytokines are necessary for this response because their depletion eliminates eosinophilia. Intriguing recent studies have demonstrated that RSV-specific CD8 T cells can inhibit Th2-mediated pulmonary eosinophilia in vvG-primed mice by as yet unknown mechanisms. Information gained from the animal models will provide important information and novel approaches for the rational design of a safe and efficacious RSV vaccine.

Immunology

The concept of forbidden foods that should not be eaten goes back to the Garden of Eden and apart from its religious meanings it may also have foreshadowed the concept of foods that can provoke adverse reactions. Thus we could say that allergic diseases have plagued mankind since the beginning of life on earth. The prophet Job was affected by a condition that following the rare symptoms described by the Holy Bible might be identified as a severe form of atopic dermatitis (AD). The earliest record of an apparently allergic reaction is 2621 B.C., when death from stinging insects was first described by hieroglyphics carved into the walls of the tomb of Pharaoh Menes depicting his death following the sting of a wasp. In 79 A.D., the death of the Roman admiral Pliny the Elder was ascribed to the SO₂-rich gases emanating from the eruption of Mount Vesuvius. Hippocrates (460–377 B.C.) was probably the first to describe how cow’s milk (CM) could cause gastric upset and hives, proposing dietetic measures including both treatment and prevention for CM allergy.

Increased expression of non-interleukin-2 T cell growth factors and their implications during liver allograft rejection in rats

BACKGROUND AND AIM

Rejection remains a problem in the transplantation field. The aim of this study was to establish acute and chronic rejection models in rats and to investigate the roles of non-interleukin (IL)-2 T cell growth factors such as IL-15, IL-7 and IL-13 during rejection.

METHODS

A liver transplant model was established using Dark Agouti and Brown Norway rats. The rats were divided into group A, left without treatment; group B, received cyclosporinee (1 mg/kg/day); and group C, cyclosporinee (4 mg/kg/day). Histopathological, reverse transcriptase-polymerase chain reaction and western blot were performed in liver specimens obtained from different time-points after transplantation in the three groups.

RESULTS

In group A, the livers showed irreversible acute cellular rejection with cell infiltration. In group B, chronic liver rejection was found, with graft infiltration, ductular damage or proliferation, obliterative arteriopathy and liver fibrosis. No apparent histological alterations were observed in group C. IL-15, IL-7 and IL-13 messenger RNA and their protein were all highly expressed in the liver specimens of groups A and B. Upregulated expression was found in IL-15 since the first day after transplantation and in IL-7 and IL-13 since day 6. The extent of IL-15 upregulation was more than that of IL-7 and IL-13.

CONCLUSIONS

Liver transplantation in Dark Agouti to Brown Norway rats with low-dose immunosuppression can induce chronic rejection. In the process of acute and chronic allograft rejections, non-IL-2 T cell growth factors such as IL-15, IL-7 and IL-13 play roles. Strategies should pay more attention to regulating these cytokines after liver transplantation.

Reduced cortical bone mass in mice with inactivation of interleukin-4 and interleukin-13

The aim of the present study was to study the in vivo role of IL-4 and IL-13 on bone metabolism. The skeletal phenotypes of male and female IL-13(-/-) (n = 7+7), IL-4(-/-)IL-13(-/-) (n = 7+7), and WT (n = 7+7) mice were compared. Analysis was made at 6 weeks of age (juvenile) by pQCT, and at 20 weeks of age (adult) by pQCT, biomechanical testing, and by S-IGF-1 and S-Osteocalcin measurements. The skeletal phenotype was affected only in adult male IL-4(-/-)IL-13(-/-) mice. These animals displayed a reduction in cortical bone mineral content (BMC) of both the tibia and the femur, as measured by mid-diaphyseal pQCT scans, compared with WT mice (tibia -8.2%; femur -8.5%; p < 0.01). This reduction in cortical BMC was due to a decreased cross-sectional area as a result of a reduced cortical thickness. The mechanical strength of the cortical bone, tested by three-point-bending at the mid-diaphyseal region of the femurs, demonstrated a significant reduction of displacement at failure (-11.4%), maximal load at failure (-10.6%), and total energy until failure (-29.4%). S-IGF-1 and S-Osteocalcin levels as well as trabecular bone mineral density (tvBMD) were unaffected in adult male IL-4(-/-)IL-13(-/-) mice. IL-4(-/-)IL-13(-/-) male mice show adult onset reduction of cortical bone mass and strength, indicating that the two anti-inflammatory Th(2) cytokines IL-4 and IL-13 are involved in the regulation of bone remodeling.

Interleukin-4 inhibition of osteoclast differentiation is stronger than that of interleukin-13 and they are equivalent for induction of osteoprotegerin production from osteoblasts

Interleukin (IL)-4 and IL-13 are closely related cytokines known to inhibit osteoclast formation by targeting osteoblasts to produce an inhibitor, osteoprotegerin (OPG), as well as by directly targeting osteoclast precursors. However, whether their inhibitory actions are the same remains unclear. The inhibitory effect of IL-4 was stronger than that of IL-13 in an osteoclast-differentiation culture system containing mouse osteoblasts and osteoclast precursors. Both cytokines induced OPG production by osteoblasts in similar time- and dose-dependent manners. However, IL-4 was stronger in direct inhibition that targeted osteoclast precursors. Furthermore, IL-4 induced phosphorylation of signal transducer and activator of transcription-6 (STAT6) at lower concentrations than those of IL-13 in osteoclast precursors. IL-4 but not IL-13 strongly inhibited the expression of nuclear factor of activated T-cells, cytoplasmic 1 (nuclear factor-ATc1), a key factor of osteoclast differentiation, by those precursors. Thus, the activities of IL-4 and IL-13 toward osteoclast precursors were shown to be different in regards to inhibition of osteoclast differentiation, whereas those toward osteoblasts for inducing OPG expression were equivalent.

Specific inhibition of interleukin-13 activity by a recombinant human single-chain immunoglobulin domain directed against the IL-13 receptor alpha1 chain

Interleukin-13 (IL-13) is a T-cell-derived pleiotropic cytokine of particular medical importance because of its critical role in the development of allergic asthma. The effects of IL-13 on its target cells are mediated through a dimeric transmembrane receptor (IL-13R), which shares the IL-4Ralpha subunit with the IL-4R system, but contains as a specific component the IL-13Ralpha1 chain. We have generated a set of single-chain Fv fragments with specific binding capacity to the extracellular domain of the human IL-13Ralpha1 receptor. Bacteriophage clones displaying receptor-binding antibody domains were selected from both naive and synthetic libraries by repetitive panning on recombinant and cell surface-expressed recombinant IL-13Ralpha1. Their specific reactivity with native human IL-13Ralpha1 expressed on the surface of transfected cells was demonstrated by flow cytometry. One binder that specifically interfered with cell activation by IL-13 was extensively characterized. This scFv inhibited IL-13-driven gene transcription and cell proliferation in test cell lines, as well as IL-13-induced activation of primary human monocytes in a dose-dependent manner, with an IC(50) below 300 nM. This novel reagent thus constitutes a valuable tool for the further elucidation of IL-13 function in disease and offers potential therapeutic perspectives.

IL-13 prolongs allograft survival: Association with inhibition of macrophage cytokine activation

Th2 cytokines, especially IL-4 and IL-10, may facilitate transplant tolerance induction but the role of IL-13, another Th2 cytokine, is not known. This study examined the effects of rat recombinant IL-13 (rIL-13) on alloimmune responses. In vitro effects of rIL-13 were compared in mixed lymphocyte cultures (MLC) on rat lymphocytes cultured with PVG stimulator cells. DA rats grafted with fully allogeneic PVG neonatal heart grafts were treated with 40,000 units of rIL-13 for 10 days and graft survival monitored by ECG. Cytokine mRNA expression in the graft and lymphoid tissues was studied by RT-PCR and alloantibody levels assayed. rIL-13 had no effect on MLC, unlike rIL-4 which enhanced proliferation and induced Th2 and inhibited Th1 cytokines in MLC. rIL-13 inhibited IL-12p35, IL-12p40 and TNF-alpha mRNA induction in dendritic cell cultures. Treatment with rIL-13 prolonged fully allogeneic PVG neonatal heart graft survival to 18-21 (13-27) days (median (range)); compared to 12 (9-15) days in untreated normal rejection (p<0.05) and 14 (10-24) days in sham treated controls (p<0.05). RT-PCR studies on graft tissue identified reduced mRNA expression for the dendritic cell/macrophage molecules iNOS, TNF-alpha and IL-12 compared to normal rejection. rIL-13 treatment did not increase Th2 cytokines as compared to normal rejection, or the Th2 dependent IgG1 alloantibody response, while IL-4 did. These studies demonstrated that rIL-13 can prolong allograft survival associated with inhibition of IL-12, TNF-alpha and iNOS mRNA induction, and suggest IL-13 could modify graft rejection by inhibition of dendritic cell and/or macrophage function.

IL-13 mediates the recruitment of reserve cells for fusion during IGF-1-induced hypertrophy of human myotubes

Insulin-like growth factor-1 (IGF-1) has been shown to induce skeletal muscle hypertrophy, to prevent the loss of muscle mass with ageing and to improve the muscle phenotype of dystrophic mice. We previously developed a model of IGF-1-induced hypertrophy of human myotubes, in which hypertrophy was not only characterized by an increase in myotube size and myosin content but also by an increased recruitment of reserve cells for fusion. Here, we describe a new mechanism of IGF-1-induced hypertrophy by demonstrating that IGF-1 signals exclusively to myotubes but not to reserve cells, leading, under the control of the transcription factor NFATc2, to the secretion of IL-13 that will secondly recruit reserve cells for differentiation and fusion. In addition, we show that IGF-1 also signals to myotubes to stimulate protein metabolism via Akt by (1) activating the mTOR-p70S6K-S6 pathway and inhibiting GSK-3β, both involved in the control of protein translation, and (2) inhibiting the Foxo1–atrogin-1 protein degradation pathway.

Expression of IL-4 receptor on non-bone marrow-derived cells is necessary for the timely elimination of Strongyloides venezuelensis in mice, but not for intestinal IL-4 production

In rodents and in humans, Strongyloides infection induces an immune response which is predominantly Th2 in nature. In an attempt to understand the role of the IL-4R/STAT6 signaling pathway, the pathway activated by the Th2 cytokines IL-4 and IL-13, in the induction of protection during Strongyloides venezuelensis infection, we have carried out experiments in mice lacking the IL-4Ralpha chain. Experiments were also carried out in STAT6 (STAT6(-/-)) and IL-12-deficient (IL-12(-/-)) mice for comparison. There was enhancement of IL-13 and abolition of IFN-gamma production in the small intestine of 7 day-infected IL-12(-/-) animals but worm elimination proceeded with very similar kinetics to those of wild-type mice. In IL-4Ralpha- or STAT6-deficient mice, there was a delay in parasite elimination and a large number of S. venezuelensis adult worms was still present in the small intestine 14 days after infection. Moreover, IgE production was completely abolished in IL-4Ralpha- or STAT6-deficient mice but tissue eosinophilia was normally induced by the parasite infection in deficient mice. Bone marrow transfer experiments showed that worm elimination occurred when a functional IL-4 receptor was present only in non-bone marrow-derived cells but not when IL-4R was only expressed in bone marrow cells. The induction of IL-4, but not IL-13, occurred independently of IL-4R. We believe these results are the first direct evidence that the mechanism responsible for the timely elimination of S. venezuelensis is dependent on the activation of IL-4R and STAT6. Moreover, a functional protective response is dependent on the expression of IL-4Ralpha on non-bone marrow-derived cells.

Tissue-Specific Function of Lymph Node Fibroblastic Reticulum Cells

OBJECTIVE

We present the first characterization of the cytokine expression pattern of lymph node fibroblastic reticulum cells (FRC), which are the stromal cells responsible for maintaining the highly structured nodal reticular fiber framework.

METHODS

Microarray expression profiles of cultured nodal FRC and dermal fibroblasts (DF) were compared as well as their response to TNF, IL-4, IL-6 and IL-13, cytokines responsible for intranodal stromal activation.

RESULTS

Hierarchical clustering of FRC and DF short-term culture samples revealed genes that were differentially expressed in FRC and DF. Identified differently regulated genes were confirmed by RNase protection analysis, PCR or immunohistochemistry. At earlier culture time points, FRC showed higher levels of several chemokines, including CCL2/MCP-1, and cytokines, e.g. IL-6, whereas several genes related to the production of extracellular matrix and angiogenesis were preferentially expressed in early DF cultures. By 60 days in culture, FRC and DF showed similar expression patterns consistent with homogenization of specialized stromal subsets. FRC and DF showed nearly identical transcriptional responses to exogenous TNF stimulation.

CONCLUSIONS

Cultured FRC showed an overall transcriptional profile similar to cultured DF, including parallel responsiveness to TNF, but with differences in the expression of chemotactic chemokines, which reflect their biological roles.

Hypernociceptive role of cytokines and chemokines: targets for analgesic drug development?

Pain is one of the classical signs of the inflammatory process in which sensitization of the nociceptors is the common denominator. This sensitization causes hyperalgesia or allodynia in humans, phenomena that involve pain perception (emotional component+nociceptive sensation). As this review focuses mainly on animal models, which don't allow discrimination of the emotional component, the terms nociception and hypernociception are used to describe overt behavior induced by mechanical stimulation and increase of nociceptor sensitivity, respectively. Pro- and anti-inflammatory cytokines and chemokines are endogenous small protein mediators released by local or migrating cells whose balance modulates the intensity of inflammatory response. The inflammatory stimuli or tissue injuries stimulate the release of characteristic cytokine cascades, which ultimately trigger the release of final mediators responsible for inflammatory pain. These final mediators, such as prostanoids or sympathetic amines, act directly on the nociceptors to cause hypernociception, which results from the lowering of threshold due to modulation of specific voltage-dependent sodium channels. Furthermore, a direct effect of cytokines on nociceptors is also described. On the other hand, there are also anti-inflammatory cytokines, such as interleukin (IL)-10, IL-4 and IL-13, and IL-1 receptor antagonists (IL-1ra), which inhibit the production of hypernociceptive cytokines and/or the final hypernociceptive mediators, preventing the installation of or the increase in the hypernociception. This review highlights the importance of the direct and indirect actions of cytokines and chemokines in inflammatory and neuropathic hypernociception, emphasizing the evidence suggesting these molecules are potential targets to develop novel drugs and therapies for the treatment of pain.

IL-4 induced MUC4 enhancement in respiratory epithelial cells in vitro is mediated through JAK-3 selective signaling

BACKGROUND

Recent studies have identified MUC4 mucin as a ligand for activation of ErbB2, a receptor tyrosine kinase that modulates epithelial cell proliferation following epithelial damage in airways of asthmatics. In this study, we investigated the potential role of IL-4, one of the Th2 inflammatory cytokines persistent in asthmatic airways, in regulating MUC4 expression using a cell line NCI-H650.

METHODS

Real time PCR analysis was performed to determine concentration and time dependent effects of IL-4 upon MUC4 expression. Nuclear run on experiments were carried out to explore potential transcriptional modulation. Western blotting experiments using a monoclonal antibody specific to ASGP-2 domain of MUC4 were performed to analyze MUC4 glycoprotein levels in plasma membrane fractions. To analyze potential signal transduction cascades, IL-4 treated confluent cultures were co-incubated, separately with a pan-JAK inhibitor, a JAK-3 selective inhibitor or a MEK-1, 2 (MAPK) inhibitor at various concentrations before MUC4 transcript analysis. Corresponding transcription factor activation was tested by western blotting using a monoclonal p-STAT-6 antibody.

RESULTS

MUC4 levels increased in a concentration and time specific fashion reaching peak expression at 2.5 ng/ml and 8 h. Nuclear run on experiments revealed transcriptional enhancement. Corresponding increases in MUC4 glycoprotein levels were observed in plasma membrane fractions. Pan-JAK inhibitor revealed marked reduction in IL-4 stimulated MUC4 levels and JAK3 selective inhibitor down-regulated MUC4 mRNA expression in a concentration-dependent fashion. In accordance with the above observations, STAT-6 activation was detected within 5 minutes of IL-4 stimulus. No effect in MUC4 levels was observed on using a MAPK inhibitor.

CONCLUSION

These observations signify a potential role for IL-4 in MUC4 up-regulation in airway epithelia.

Induction of uteroglobin-related protein 2 (Ugrp2) gene expression by the Th2 cytokines IL-4 and IL-13

Uteroglobin-related proteins 1 and 2 (UGRP1 and -2) are thought to play important roles in inflammation and immunologic responses in the lung. In this study we demonstrate that IL-4 and IL-13 enhance Ugrp2 gene expression in the mouse transformed Clara cell line, mtCC, in a time- and dose-dependent manner. Addition of actinomycin D abrogated the IL-4- and IL-13-induced increase of Ugrp2 expression, demonstrating that this increase occurs at the transcriptional level. When mtCC cells were pretreated with IFN-gamma before the addition of IL-4 or IL-13, IL-4- and 13-induced Ugrp2 mRNA increase was markedly decreased. IL-4 and IL-13 induced phosphorylation of STAT6 in mtCC cells, which binds to the proximal STAT-binding element (SBE) in the Ugrp2 gene promoter, leading to transcriptional activation of this gene. Mutations of the proximal SBE abrogated the binding of activated STAT6 to this site and the IL-4-induced increase in Ugrp2 gene promoter activity. IFN-gamma-activated STAT1 binds to the same SBE in the Ugrp2 gene promoter to which STAT6 binds and decreases the binding of STAT6 to this site. Furthermore, an IL-4-induced increase in Ugrp2 expression was not observed in primary cultures of lung cells derived from STAT6-deficient mice. These results indicate that Ugrp2 expression is enhanced by IL-4 and IL-13 through STAT6 binding to the proximal SBE located in the Ugrp2 gene promoter.

The effect of hydrodynamics-based delivery of an IL-13-Ig fusion gene for experimental autoimmune myocarditis in rats and its possible mechanism

Interleukin (IL)-13 is a pleiotropic cytokine secreted by activated Th2 T lymphocytes. Th1 cytokines are assumed to exacerbate and Th2 cytokines to ameliorate rat experimental autoimmune myocarditis (EAM). Here, we examined the effect of IL-13 on EAM, using a hydrodynamics-based delivery of an IL-13-Ig fusion gene, as well as the possible mechanism of its effect. Rats were immunized on day 0, and IL-13-Ig-treated rats were injected with pCAGGS-IL-13-Ig, and control rats with pCAGGS-Ig, on day 1 or 7. On day 17, the IL-13-Ig gene therapy was effective in controlling EAM as monitored by a decreased heart weight/body weight ratio, by reduced myocarditis and by reduced atrial natriuretic peptide mRNA in the heart, as a heart failure marker. On the basis of IL-13 receptor mRNA expression in separated cells from EAM hearts, we proposed that IL-13-Ig target cells were CD11b(+) cells and non-cardiomyocytic noninflammatory (NCNI) cells, such as fibroblasts, smooth muscle or endothelial cells. IL-13-Ig inhibited expression of the genes for prostaglandin E synthase, cyclooxygenase-2, inducible nitric oxide synthase, IL-1beta and TNF-alpha in cultivated cells from EAM hearts, while it enhanced expression of the IL-1 receptor antagonist gene. We conclude that IL-13-Ig ameliorates EAM and suppose that its effectiveness may be due to the influence on these immunologic molecules in CD11b(+) and NCNI cells.

Interleukin-4 (IL-4) pathway

Interleukin-4 (IL-4) is a cytokine produced by T(H)2 type helper T cells and by mast cells, basophils, and eosinophils. This cytokine can elicit many responses, some of which are associated with allergy and asthma. Studies with long-term cell lines and primary cells have revealed differences in the signaling between these two experimental systems. Understanding these differences is important because therapeutic strategies targeting IL-4 and its signaling pathways are currently being tested to treat allergy and asthma.

Expression of interleukin-21 receptor in epidermis from patients with systemic sclerosis

OBJECTIVE

To examine the expression and regulation of interleukin-21 (IL-21) and IL-21 receptor (IL-21R) in patients with systemic sclerosis (SSc; scleroderma).

METHODS

Skin biopsy specimens were obtained from 23 patients with SSc and 15 healthy controls. IL-21/IL-21R messenger RNA (mRNA) was quantified using real-time polymerase chain reaction (PCR). The expression pattern of IL-21/IL-21R was analyzed by in situ hybridization and Western blotting. Stimulation experiments were performed with cultured dermal fibroblasts from patients with SSc and healthy controls as well as with keratinocytes, using IL-1beta, platelet-derived growth factor BB, monocyte chemoattractant protein 1, transforming growth factor beta, and IL-21. The SCID-hu skin mouse model was used for in vivo experiments.

RESULTS

IL-21R mRNA was detected in all biopsy specimens from patients with SSc and controls, with a 4.7-fold increase observed in SSc samples. In situ hybridization and immunohistochemical analysis showed an up-regulation of IL-21R in samples of epidermis from SSc patients, whereas no signal was detected in skin specimens from healthy controls. These results were confirmed in vitro, in that cultured keratinocytes expressed significant levels of IL-21R, whereas no signal was observed in fibroblasts. Interestingly, mRNA for IL-21 could not be detected by real-time PCR and in situ hybridization. Various concentrations of key cytokines in the pathogenesis of SSc did not stimulate the expression of IL-21R mRNA in cultured keratinocytes and dermal fibroblasts. In the SCID mouse transplantation model, the overexpression of IL-21R mRNA in SSc keratinocytes remained unchanged after transplantation.

CONCLUSION

The up-regulation of IL-21R in keratinocytes indicates that, similar to fibroblasts and endothelial cells, the expression pattern is altered in SSc. Moreover, the expression of IL-21R appears to be independent of key cytokines that are operant in SSc.

Stat 4 but not Stat 6 mediated immune mechanisms are essential in protection against plague

The Caf1 and LcrV sub-unit vaccine for plague has been shown to be highly protective against challenge with virulent Yersinia pestis in a mouse model. Production of large amounts of IgG1 in response to the vaccine correlates with protection against aerosol and parenteral infection. In this study the effect of genetic mutation in the immune system on protection was addressed. Stat 6(-/-) mice which are unable to utilise the type 2 cytokines IL-4 and IL-13 and so should have reduced IgG1 responses were utilised in order to determine whether an immune system biased towards the type 1 axis could mount an effective response to the vaccine. Conversely in the Stat 4(-/-) mouse model, IL-12 and interferon-gamma-mediated immune mechanisms are inactive and the immune response should be biased towards the type 2 axis. Serum antibody responses to vaccination in both the knockout strains and their wild type controls revealed little difference in levels of IgG and isotype profiles. Elispot analysis of cytokine production at the single cell level did however reveal a functional defect in the Stat 4(-/-) mice which had low levels of IFN-gamma producing cells. Following virulent challenge, the Stat 6(-/-) mice showed high levels of protection, while the Stat 4(-/-) mice were poorly protected, indicating a fundamental defect in their immune systems which could not be overcome even by the passive transfer of CD4(+) cells from immunised BALB/c donors. It appears therefore that type 1 immune mechanisms, activated following Stat 4 phosphorylation, are essential in protection against plague.

Determination of interleukin-4-responsive region in the human cytochrome P450 2E1 gene promoter

Cytochrome P450 2E1 (CYP2E1) gene expression is known to be induced by interleukin-4 (IL4) and repressed by inflammatory cytokines, such as interleukin-1beta3 (IL1beta3) in human hepatocytes. The mechanisms involved in these transcriptional regulations remain elusive. In order to study these mechanisms, various constructs of the human CYP2E1 promoter were prepared and transfected into the human HepG2 hepatoma cell line. Our findings revealed that an IL4-responsive region of 128bp (-671/-544) was required to mediate induction by IL4. IL1beta caused moderate but significant decrease of the promoter activity, which was abolished when the two cytokines were combined. The IL1beta inhibitory effect is mediated through a regulatory sequence independent of that of IL4. Furthermore, by using specific signaling pathway inhibitors, we demonstrated that IL4 activation required protein kinase C (PKC) activation. In addition, our results suggest that induction by IL4 was not dependent on a single binding site but rather on a complex region which includes putative binding sites for signal transducer and activator of transcription (STAT)6, activator protein (AP)-1, nuclear factor kappa-B (NFkappaB), nuclear factor of activated T cells (NFAT) and CCAAT enhancer binding protein (C/EBP). Electrophoretic mobility shift assays suggest that AP1 and NFAT transcription factors are able to bind to three sites in the IL4-responsive region.

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

As interleukin (IL)-13 and IL-4 play a major role in various diseases including asthma, allergy, and malignancies, it is desirable to generate a molecule that blocks the effects of both cytokines. We previously generated a human IL-13 mutant (IL-13E13K), which is a powerful antagonist of IL-13, blocking the biological activities of IL-13. We now show that IL-13E13K also competitively inhibits signaling and biological activities of IL-4 through type II and partially through type III IL-4 receptor (R) system. IL-13E13K completely blocked the IL-4-induced phosphorylation of STAT6 and IL-4-dependent protein synthesis in cells expressing type II and partially type III IL-4R but not type I IL- 4R. Consistent with the inhibition of biological activities, IL-13E13K inhibited IL-4 binding to type II IL-4R-expressing cells but not to type I IL-4R-expressing cells. The inhibition efficiency of IL-4 binding by IL-13E13K was relatively lower compared to wtIL-13 even though IL-13E13K bound to IL-13Ralpha1 positive cells with a similar affinity to wtIL-13. These results indicate that Glu13 in IL-13 associates with IL-4Ralpha, and mutation to lysine decreases its binding ability to IL-4Ralpha chain. IL-13E13K binds to IL- 13Ralpha1, which is shared by both IL-13R and IL-4R systems. Consequently, IL-13E13K inhibits IL-4 binding to these cells and prevents heterodimer formation between IL-13Ralpha1 and IL-4Ralpha chains. This interference by IL-13E13K blocks the biological activities of not only IL-13 but also partially of IL-4. Thus, IL-13E13K may be a useful agent for the treatment of diseases such as asthma, allergic rhinitis, and cancer, which are dependent on signaling through both IL-4 and IL-13 receptors.

Expression of interleukin-13 receptor alpha 1-subunit on peripheral blood eosinophils is regulated by cytokines

Interleukin-13 (IL-13) is critical for the development of allergic asthma and is involved in the activation of eosinophils within the airways. IL-13 exerts its activity on target cells via the dimeric IL-13 receptor (IL-13R), which comprises the IL-13 receptor alpha1-chain (IL-13Ralpha1) as a specific component. The aim of this study was to investigate the expression of the IL-13Ralpha1-chain on primary human eosinophilic granulocytes. Furthermore, it addresses the regulatory influence of cytokines on the level of surface abundance of this receptor subunit. Expression of IL-13- and IL-4-receptor subunits in purified primary human eosinophils was monitored at the messenger RNA level by reverse transcription polymerase chain reaction and at the protein level by flow cytometry. For the analysis of IL-13Ralpha1 surface expression, a new monoclonal antibody, which was generated using genetic immunization, was employed. Different cytokines with established activity on eosinophils were studied with regard to their influence on IL-13Ralpha1 in vitro by flow cytometry. Whereas IL-13 and IL-4 had inhibitory effects on IL-13Ralpha1 expression on eosinophils, interferon-gamma, tumour necrosis factor-alpha, and, to the largest extent, transforming growth factor-beta, enhanced the expression of this receptor subunit. A positive regulatory response evoked by transforming growth factor-beta and interferon-gamma does not prevent inhibitory effects caused by IL-13. These findings suggest a regulatory cytokine network influencing the reactivity of eosinophils to IL-13.

Interleukin-4 and interleukin-13 potentiate interleukin-1 induced secretion of interleukin-6 in human osteoblast-like cells

Formation of interleukin-6 (IL-6) in osteoblasts and bone marrow stromal cells is believed to regulate osteoclast recruitment. The anti-inflammatory cytokines interleukin-4 and -13 (IL-4 and IL-13) stimulate IL-6 production in human osteoblasts. We investigated the relative potencies, and synergistic effects, between IL-4, IL-13 and interleukin-1 (IL-1) on IL-6 formation in human osteoblast-like cells. Isolated human osteoblast-like cells were incubated for 72 h in the presence of various concentrations of IL-4, IL-13 and IL-1, and IL-6 secretion was measured by ELISA. All cytokines stimulated the secretion of IL-6. The rank order of potency was IL-1>>IL-4>IL-13. There were no additive or synergistic effects between IL-4 and IL-13. However, co-stimulation with IL-1 and IL-4 resulted in a marked synergistic effect on IL-6 secretion. Co- stimulation with IL-1 and IL-13 gave a minor synergistic effect. In conclusion, IL-4/13 synergistically potentiates IL-1 induced secretion of IL-6 in human osteoblast-like cells.

Complex role of the IL-4 receptor alpha in a murine model of airway inflammation: expression of the IL-4 receptor alpha on nonlymphoid cells of bone marrow origin contributes to severity of inflammation

Recent studies have suggested the IL-4Ralpha expressed on lung epithelium is necessary for TH2-mediated goblet cell differentiation and mucus hypersecretion in a murine model of allergic lung disease. However, the IL-4Ralpha is expressed on numerous cell types that could contribute to the overall pathology and severity of asthma. The relative role of the receptor on these cells has not yet been conclusively delineated. To dissect the contribution of IL-4Ralpha in the development of pulmonary allergic responses, we generated murine radiation bone marrow (BM) chimeras. BM from IL-4Ralpha(+) or IL-4Ralpha(-) mice was transferred into recipient mice that expressed or lacked IL-4Ralpha. In the absence of IL-4Ralpha in recipient mice, there was no goblet cell metaplasia or mucus hypersecretion in response to OVA, even in the presence of TH2 cells and substantial eosinophilic infiltration. More importantly, we found that expression of the IL-4Ralpha on a nonlymphoid, MHC class II(+), BM-derived cell type contributes to the severity of inflammation and mucus production. These results suggest that IL-4 and IL-13 contribute to the development of allergic inflammation by stimulating a complex interaction between IL-4Ralpha(+) cell types of both bone marrow and non-bone marrow origin.

Regulation of arginase expression by T-helper II cytokines and isoproterenol

BACKGROUND

Trauma causes a release of catecholamines, transforming growth factor-beta (TGF-beta), and T-helper II cytokines (TH2). Individually, these substances also induce arginase in macrophages. The purpose of this study was to determine the synergistic interactions between isoproterenol, TGF-beta, and TH2 cytokines on arginase expression in macrophages.

METHODS

Confluent RAW 264.7 macrophages were incubated with various combinations of interleukins 4, 10, and 13 (IL-4, IL-10, IL-13), and TGF-beta with isoproterenol over 48 hours. Arginase activity, as well as arginase I expression by Western blot and reverse transcriptase-polymerase chain reaction, were measured.

RESULTS

Although isoproterenol, IL-4, IL-10, and IL-13 individually induced arginase, significant synergy between the combination of isoproterenol with either TGF-beta or the TH2 cytokines was observed. All cytokines except IL-10 also induced arginase I protein and mRNA. Arginase II protein was detected in cells exposed to IL-10.

CONCLUSIONS

We conclude that isoproterenol synergizes with IL-4, IL-13, and TGF-beta to increase arginase I mRNA and protein, as well as arginase activity in RAW 264.7 macrophages. Further, IL-10 synergizes with isoproterenol to increase arginase activity and arginase II protein. These synergistic mechanisms may compete with nitric oxide synthase for l-arginine substrate, thus shunting away available arginine from nitric oxide production and contributing to cellular immunosuppression observed after trauma.

Interleukin-13 overexpression by tax transactivation: a potential autocrine stimulus in human T-cell leukemia virus-infected lymphocytes

The human T-cell leukemia virus type 1 (HTLV-1) Tax oncoprotein induces growth transformation and is critical for the pathogenesis of the HTLV-1-induced adult T-cell leukemia (ATL). It stimulates the cell cycle and transactivates cellular genes. Here we show that the expression of interleukin-13 (IL-13) is upregulated as a consequence of Tax in HTLV-1-transformed T cells and ATL-derived cultures. IL-13 exerts proliferative and antiapoptotic functions and is linked to leukemogenesis, since it stimulates Hodgkin lymphoma cells by an autocrine mechanism. Overexpression of IL-13 RNA and protein was confirmed in HTLV-1-positive and Tax-transformed cells. Induction of endogenous IL-13 levels in tax-transfected Jurkat cells and in conditional Tax-expressing transformed T lymphocytes suggested that Tax can replace signals required for IL-13 synthesis. For functional analysis, the IL-13 promoter and deletion variants were cloned into luciferase reporter plasmids. Experiments with transfected human T lymphocytes revealed a 16-fold stimulation of the IL-13 promoter by Tax. Experiments with Tax mutants indicated that none of the classical transactivation pathways (SRF, CREB, and NF-kappaB) is sufficient for the transactivation; at least two different Tax functions are required for full transactivation. The IL-13 promoter is stimulated via two elements; one is a NF-AT binding P element, and the other is a putative AP-1 site. The following observations suggest that IL-13 may stimulate HTLV-1-transformed cells by an autocrine mechanism: (i) the HTLV-1-transformed cells express the IL-13 receptor on their surface, and (ii) STAT6, a downstream effector of IL-13 signaling, is constitutively activated. Thus, in summary, Tax, by transactivating the promoter, induces IL-13 overexpression that possibly leads to an autocrine stimulation of HTLV-1-infected cells.

Transgenic Expression of Insulin Receptor Substrate 2 in Murine B Cells Alters the Cell Density-Dependence of IgE Production In Vitro and Enhances IgE Production In Vivo

Previous studies have shown that insulin receptor substrate (IRS)1 and IRS2 mediate proliferative and antiapoptotic signaling through the IL-4R in 32D cells; however their role in regulating normal B cell responses is not clear. To investigate the role of IRS2 in normal B cell function, we developed IRS2 transgenic (Tg) mice on the C57BL/6 background. Western blot analysis revealed a 2-fold elevation in IRS2 protein levels in Tg(+) mice compared with littermate controls and a 3-fold increase in basal tyrosine phosphorylated IRS2 in the absence of IL-4 stimulation. IL-4-induced tyrosine phosphorylation of IRS2 was elevated in Tg(+) B cells, whereas IL-4-induced phosphorylation of STAT6 was similar between Tg(+) and Tg(-) B cells. Tg expression of IRS2 had little effect on IL-4-mediated proliferation and no effect on protection from apoptosis. However, production of IgE and IgG1 by Tg(+) B cells using standard in vitro conditions was diminished 50-60%. Because Ig production in vitro is known to be highly cell concentration-dependent, we performed experiments at different cell concentrations. Interestingly, at very low B cell concentrations (1000-5000 B cells/well), IgE and IgG1 production by Tg(+) B cells was greater than that of controls, whereas at higher cell concentrations (10,000-20,000 cells/well) Ig production by Tg(+) B cells was less than controls. Furthermore, in vivo immunization with OVA-alum or goat anti-IgD resulted in elevated serum IgE levels in the Tg(+) mice. These results indicate that overexpression of IRS2 alters the B cell intrinsic density-dependence of IgE and IgG1 production in vitro and enhances IgE responses in vivo.

Biology and therapeutic potential of the interleukin-4/interleukin-13 signaling pathway in asthma

The future management of patients with allergic asthma is poised to change in the coming one to two decades. This prediction is based on fundamental new insights into the pathogenesis of disease, gained through the study of both humans and experimental models of asthma. These studies have revealed that allergic asthma is an immune-mediated disease which, despite the redundancy characteristic of all immune responses, may be induced through a single dominant signaling cascade called the interleukin (IL)-4/IL-13 signaling pathway. In addition to the cytokine IL-4, this pathway includes IL-13, the cytokine receptor subunit IL-4 receptor alpha (IL-4Ralpha), Janus-associated tyrosine kinases and the transcription factor, signal transducer and activator of transcription 6. The IL-4 signaling pathway controls the most important cellular developmental (afferent) events that underlie asthma. These include T helper (Th) type 2 cell activation, B cell activation and immunoglobulin (Ig) E secretion, mast cell development, and effector (efferent) events related exclusively to immune effects on the lung such as goblet cell metaplasia and airway hyperresponsiveness. Any of the IL-4 signaling molecules are potentially amenable to pharmacological intervention, but a detailed understanding of the entire pathway is required to appreciate their actual potential for drug development. For example, neutralization strategies that target only IL-4 are unlikely to succeed because they leave IL-13 free to continue the signaling cascade. In contrast, neutralization of IL-4Ralpha may represent a more feasible strategy, as it should prevent signaling by both IL-4 and IL-13. The therapeutic potential of targeting intracytoplasmic tyrosine kinases has already been achieved with the use of small molecules, suggesting that this approach may be realistically adopted for the treatment of asthma. However, well designed asthma clinical trials are warranted to determine with certainty, the efficacy of therapies based on IL-4/IL-13 blockade.