Safety of dupilumab in T2 airways conditions: focus on eosinophilia across trials and real-life evidence

INTRODUCTION

Dupilumab, a monoclonal antibody targeting the IL-4 receptor alpha subunit, effectively blocks both IL-4 and IL-13 mediated pathways. Its introduction has represented a significant advancement in the treatment of severe asthma and other Type 2 (T2) conditions, including nasal polyps, atopic dermatitis, and eosinophilic esophagitis. To date, Dupilumab has demonstrated optimal efficacy and safety profile.

AREAS COVERED

The safety profile of dupilumab has been extensively studied, especially for its effects on blood eosinophil count. Transient eosinophil increase during treatment is typically insignificant from a clinical point of view and related to its mechanism of action. Rare cases of hyper-eosinophilia associated with clinical conditions like eosinophilic granulomatosis with polyangiitis (EGPA) and hypereosinophilic syndrome (HES) have been reported. Those cases are often related to the drug's steroid-sparing effect or the natural trajectory of the underlying disease rather than a direct cause-effect relationship with dupilumab.

EXPERT OPINION

The management of hyper-eosinophilia during dupilumab treatment requires comprehensive diagnostic work-up and strict follow-up monitoring for early detection of systemic disease progression in order to avoid unnecessary discontinuation of an effective treatment. This approach highlights the importance of a personalized treatment.

Anti-cancer activity of microbubble conjugated with Sorafenib containing liposome and IL4R-targeting peptide in kidney cancer cells

Microbubble-based cancer treatment is a promising new approach that utilizes tiny gas-filled bubbles to deliver cancer drugs directly to tumor sites. This study aims to investigate the anti-cancer effect of the novel microbubble (MB) complex conjugated with sorafenib containing liposome and interleukin 4 receptor (IL4R) targeting peptide in kidney cancer cells. MBs were synthesized by using a solvent with an emulsion evaporation technique. To target kidney tumor cells, the produced MBs were conjugated with sorafenib (SOR) loaded liposomes and peptide ligands for (IL4RTP). The anti-cancer effect of the MB complex was accessed by WST-1 assay, confocal microscopy analysis, and western blotting analysis. The finally prepared IL4RTP (MB-Lipo(SOR)-IL4RTP) showed an average size of 1,600 nm. A498, a kidney cancer cell line that expresses IL4Rα strongly, had an uptake of the MB-Lipo(SOR)-IL4RTP when exposed to frequency ultrasonic energy. Additionally, MB-Lipo(SOR)-IL4RTP suppressed the growth of A498 cells in an IL4R-dependent manner. This cell proliferation assay results were validated by western blotting analysis of the signal transduction proteins such as FOXO3, phosphorylated Erk, total Erk, and p27. Taken together, these findings show that MB-Lipo(SOR)-IL4RTP exerts the effective targeting capacity for A498 kidney cancer cells via regulation of Erk phosphorylation as a promising ultrasound contrast and therapeutic agent for treating kidney cancers.

Identification of clinical predictors for dupilumab dose spacing in adults with atopic dermatitis: a real-world study

BACKGROUND

Dupilumab is a monoclonal antibody against the IL-4/IL-13 receptor-subunit approved for the treatment of moderate-severe atopic dermatitis (AD). Some attempts to increase dose interval have been described in both trial and real-world settings.

OBJECTIVE

This study aimed to identify predictive clinical and demographic factors affecting patient selection for dose spacing or treatment withdrawal due to satisfactory response.

MATERIALS AND METHODS

This retrospective study included adult patients with moderate-to-severe AD treated with dupilumab for at least 16 weeks. Descriptive statistics were performed to analyze demographic and clinical variables. Logistic regression models were used to identify predictor variables.

RESULTS

A total of 818 adult patients with moderate-to-severe AD was included in the study and 12% (97/818) of them performed dose spacing to 3-4 weeks or treatment withdrawal (8%, 67/818). The presence of non-cutaneous atopic manifestations (OR = 1.59, 95%CI = 1.06-2.38, p = 0.024), prurigo nodularis phenotype (OR = 4.5, 95%CI = 1.87-10.9, p = 0.001) and the age at treatment initiation (OR = 1.82, 95%CI = 1.12-2.94, p = 0.015) were confirmed as the strongest predictors of dose spacing or treatment withdrawal while maintaining dupilumab effectiveness.

CONCLUSION

Our findings contribute to define the patient profile that could maintain the therapeutic response after dose spacing or treatment withdrawal.

IgG memory B cells expressing IL4R and FCER2 are associated with atopic diseases

BACKGROUND

Atopic diseases are characterized by IgE antibody responses that are dependent on cognate CD4 T cell help and T cell-produced IL-4 and IL-13. Current models of IgE cell differentiation point to the role of IgG memory B cells as precursors of pathogenic IgE plasma cells. The goal of this work was to identify intrinsic features of memory B cells that are associated with IgE production in atopic diseases.

METHODS

Peripheral blood B lymphocytes were collected from individuals with physician diagnosed asthma or atopic dermatitis (AD) and from non-atopic individuals. These samples were analyzed by spectral flow cytometry, single cell RNA sequencing (scRNAseq), and in vitro activation assays.

RESULTS

We identified a novel population of IgG memory B cells characterized by the expression of IL-4/IL-13 regulated genes FCER2/CD23, IL4R, IL13RA1, and IGHE, denoting a history of differentiation during type 2 immune responses. CD23+ IL4R+ IgG+ memory B cells had increased occurrence in individuals with atopic disease. Importantly, the frequency of CD23+ IL4R+ IgG+ memory B cells correlated with levels of circulating IgE. Consistently, in vitro stimulated B cells from atopic individuals generated more IgE+ cells than B cells from non-atopic subjects.

CONCLUSIONS

These findings suggest that CD23+ IL4R+ IgG+ memory B cells transcribing IGHE are potential precursors of IgE plasma cells and are linked to pathogenic IgE production.

Polymorphisms of IL-4 and IL-4R are associated to some demographic characteristics of differentiated thyroid cancer patients but are not determinants of risk in the Brazilian population

BACKGROUND

IL-4 is known to present abnormal expression in thyroid tumors and SNPs in the IL-4 and its receptor IL-4R genes are associated to risk and mortality of various types of cancer.

METHODS

In order to evaluate their role in differentiated thyroid cancer (DTC), we investigated genetic frequencies of two IL-4 promoter SNPs (rs2070874 C>T, rs2243250 C>T) and four non-synonymous SNPs of the IL-4R gene (rs1805010 A>G, rs1805012 C>T, rs1805013 C>T, rs1801275 A>G) in 300 DTC patients matched to 300 controls. All patients were managed according to current guidelines and followed-up for a period of 12-252 months (69.20 ± 52.70 months).

RESULTS

Although none of the six investigated SNPs showed association with risk of DTC, rs1805010 was associated with age of diagnosis and the SNPs rs1805012 and rs1801275 were associated to gender. Further, in-silico analysis showed that all these three SNPs were able to cause decreased stability of the protein. We were not able to demonstrate any other association to clinical features of aggressiveness or to patients' prognosis.

CONCLUSIONS

These findings indicate that although genetic variants in IL-4 and IL-4R do not influence the risk or outcome of DTC patients, their influence on the behavior of thyroid tumors deserves further investigation.

Cyclosporine 0.1% (Ikervis®) treatment in steroid-dependent dupilumab-associated conjunctivitis

Dupilumab is a drug that has recently been approved by the Food and Drug Administration (FDA) and European Medical Agency (EMA) for the treatment of moderate-to-severe atopic dermatitis in adults. An increase in frequency of conjunctivitis related to dupilumab treatment has been reported in recent publications and clinical trials. We report two steroid-dependent cases satisfactorily treated with cyclosporine 0.1% (Ikervis^®). To our knowledge there are no reported cases of dupilumab-associated conjunctivitis treated with cyclosporine 0.1% (Ikervis^®).

[Ocular symptoms associated with dupilumab in atopic dermatitis]

BACKGROUND

Dupilumab, the first registered biological for the treatment of atopic dermatitis, frequently causes adverse ocular events. These often take the form of mild conjunctivitis or blepharoconjunctivitis, however, more serious adverse ocular events have also been reported, including limbal stem cell insufficiency.

CASE DESCRIPTION

A 56-year-old man was treated with dupilumab for severe atopic dermatitis. His eczema improved greatly, but he developed bilateral conjunctivitis with limbal stem cell insufficiency in his right eye. After discontinuation of dupilumab, the eye symptoms gradually disappeared. After three months no conjunctivitis or limbal stem cell insufficiency was observed on ophthalmological examination.

CONCLUSION

Adverse ocular events are often seen in the treatment of atopic dermatitis with dupilumab. Caution is advised if severe adverse events occur. Therefore, it is important to identify the underlying pathophysiological mechanism of these adverse events.

[Correlation of gene polymorphism of interleukin 4 receptor alpha peptide chain and total serum IgE levels in asthmatic children in Guiyang area]

OBJECTIVE

To explore the correlation of gene polymorphism of interleukin 4 receptor alpha chain (IL-4Rα) and total serum IgE levels in children of bronchial asthma in Guiyang area.

METHODS

A total of 160 asthmatic children at Affiliated Hospital, Guiyang Medical College from August 2010 to February 2011 were selected as asthma group. There were 96 males and 64 females with an average age of (6.9 ± 3.3) years. During the same period, 143 healthy children from outpatient physical examination center of this hospital were chosen as control group. There were 75 males and 68 females with an average age of (4.9 ± 3.9) years. Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and allele-specific polymerase chain reaction (AS-PCR) were used to determine the polymorphisms of Q576R on exon 12 and I75V on exon 5 of IL-4Rα in both groups. The total serum IgE levels were determined by enzyme-linked immune sorbent assay (ELISA). Comparisons of two groups were made for genotype and allele frequency, serum total IgE and different genotypes, different groups of total serum IgE levels.

RESULTS

Three genotypes of AA, AG and GG existed on Q576R and I75V loci between two groups. The genotypic frequencies of two loci had significant differences in two groups (χ(2) = 30.972, 16.776, both P < 0.001). The subjects with variant allele on Q576R and I75V loci had higher risks for asthma than those without variant allele (χ(2) = 33.236, 13.845, both P < 0.001). The total serum levels of IgE in asthma group were higher than those in control group ((312 ± 297) vs (61 ± 48) U/ml, t = 9.959, P < 0.001). However, these three genotypes of two loci showed no significant inter-group difference (all P > 0.05). In mutation allele carriers and non-carriers of Q576R locus, total IgE levels showed no significant difference (t = -0.028, 1.279; P = 0.978, 0.203). Differences in total IgE levels between I75V polymorphic variant allele carriers and non-carriers were also not statistically significant in control group (t = -0.763, P = 0.447). However, in asthma group, total IgE levels of I75V polymorphic variant allele carriers were significantly higher than those of non-carriers (t = -2.112, P = 0.036).

CONCLUSIONS

The 576 and 75 loci of IL-4Rα are important candidate genes of asthmatic children in Guiyang area. And the serum total IgE levels of variant allele G at 75 locus in IL-4Rα are higher than those without it.

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

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

Associations of a novel IL4RA polymorphism, Ala57Thr, in Greenlander Inuit

BACKGROUND

A novel IL4RA polymorphism, Ala57Thr, was identified in Greenlander Inuit.

OBJECTIVE

We sought to determine whether the novel Thr57 allele is population specific and to assess the associations of Ala57Thr and Ile50Val with atopy in 2 Inuit populations.

METHODS

Ala57Thr and Ile50Val were genotyped in 651 Inuit living in Denmark, 1295 Inuit living in Greenland, and 1329 individuals from 7 populations from widely differing global locations. In Inuit the polymorphisms were evaluated for associations with atopy, rhinitis, asthma, and pulmonary function.

RESULTS

Thr57 was in linkage disequilibrium with Ile50 (D' = 1, r(2) = 0.13) and was common (33%) in the Inuit but rare (<0.6%) in all other populations. In Inuit living in Denmark, the Thr57 allele (in a dose-dependent manner) and the Ile50/Thr57 haplotype were associated with lower risk of atopy (P(linear) = .003 and P = .034, respectively), with similar trends observed for atopic rhinitis and atopic asthma. In Inuit living in Greenland, Thr57 was not associated with atopy or atopic diseases, but Ile50 was weakly associated with lower risk of atopy.

CONCLUSION

The novel IL4RA Ala57Thr was common in and population specific to Greenlander Inuit, with Thr57 associated with a lower risk of atopy in those living in Denmark. Hence a full investigation of genotype-phenotype relationships in a given population can only be achieved if each gene is screened for novel polymorphisms in that population.

CLINICAL IMPLICATIONS

Clinical risk attributable to variations in a gene in an ethnic group requires that all variations of the gene are known for that group.

Associations of the IL2Ralpha, IL4Ralpha, IL10Ralpha, and IFN (gamma) R1 cytokine receptor genes with AIDS progression in a French AIDS cohort

We have performed an extensive analysis of Th1/Th2 cytokine receptors IL2Ralpha, IL4Ralpha, IL10Ralpha, and IFNgammaR1 gene polymorphisms to evaluate their impact on AIDS progression. The coding regions and promoters of these genes were sequenced in the genetics of resistance to immunodeficiency virus cohort, composed of 327 HIV-1-positive patients with extreme progression phenotypes, slow and rapid progressors, and of 446 healthy control subjects, all of them of Caucasian descent. Overall, 104 single nucleotide polymorphisms and four insertions/deletions with a minor allelic frequency higher than 1% were identified, 21 of them being newly characterized. We observed weak associations for 13 polymorphisms of IL2Ralpha, IL4Ralpha, IL10Ralpha, and IFNgammaR1, and 11 haplotypes of IL2Ralpha, IL4Ralpha, and IFNgammaR1. However, we could not relate these positive signals to any relevant biological information on the gene function. To affirm these putative associations in AIDS, further confirmation on other AIDS cohorts will be needed. This complete catalog of polymorphisms in IL2Ralpha, IL4Ralpha, IL10Ralpha, and IFNgammaR1 cytokine receptor genes should also be useful for investigating associations in other immune-related diseases.

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.

Association of theIL4R single-nucleotide polymorphism I50V with rapidly erosive rheumatoid arthritis

OBJECTIVE

To examine whether single-nucleotide polymorphisms (SNPs) of the interleukin-4 receptor gene IL4R influence susceptibility to, or radiographic progression in, rheumatoid arthritis (RA).

METHODS

The contribution of 2 SNPs (I50V and Q551R) in the coding region of IL4R to RA susceptibility was analyzed by allele-specific polymerase chain reaction in a case-control study of 471 RA patients and 371 healthy controls. Patients with available radiographs of the hands and feet obtained 2 years after disease onset (n = 302) were stratified retrospectively according to radiologic outcome into an erosive and a nonerosive group to evaluate the association between IL4R SNPs and disease progression.

RESULTS

No differences in the genotype and allele frequencies of the I50V or Q551R SNPs were identified between the RA patients and healthy controls. In contrast, significant differences in the distribution of I50V IL4R SNP genotypes between patients with erosive and nonerosive disease were observed (chi2 = 15.68, P = 0.0004). Bone erosions at 2 years after disease onset were present in 68.1% of patients homozygous for the V50 allele compared with 37.0% of patients homozygous for the I50 allele (odds ratio 3.86, P < 0.0001). This association was independent of individual factors previously associated with severe disease, such as rheumatoid factor or the HLA-DR shared epitope. On a cellular level, the V50 allele conferred significantly reduced responsiveness to interleukin-4, providing a possible mechanism for the association of the I50V IL4R polymorphism with early erosions in RA.

CONCLUSION

Our data identify the I50V IL4R SNP as a novel genetic marker in RA, showing high predictive value for early joint destruction.

Polymorphisms in the interleukin-4 receptor alpha chain gene influence susceptibility to HIV-1 infection and its progression to AIDS

Interleukin (IL) 4 is a key T helper-2 cytokine that downregulates and upregulates CCR5 and CXCR4, respectively, the main coreceptors for HIV. Our objective is to investigate whether single-nucleotide polymorphisms (SNPs) in the IL-4 receptor alpha chain gene (IL4RA) affect HIV infection and its progression to AIDS. The I50V SNP in exon 5 and the haplotypes of six SNPs in exon 12 (E375A, C406R, S411L, S478P, Q551R, and V554I) were studied by polymerase chain reaction and sequencing in 30 HIV+ long-term nonprogressors (LTNP), 36 HIV+ typical progressors (TP), 55 highly exposed but uninfected individuals (EU), 25 EU-sexuals (EU-Sex; mostly women) and 30 EU-hemophiliacs (EU-Hem; hepatitis C virus+), and 97 healthy controls (HC), all Caucasians and lacking CCR5Delta32 homozygosity. V50 homozygosity was increased in LTNP (44%) compared with the other groups [p = 0.005; relative risk ratio = 3.4, 95% confidence interval (CI) = 1.12-10.6, p = 0.03]. The most common (C) exon 12 haplotype, ECSSQV, predominated in all groups, but uncommon (U) haplotypes were increased in HIV+ individuals (n = 64), especially in those (51 of 64) infected via parenteral exposure (35.3%) compared with HC (20.4%) and EU-Hem (18.4%) [p = 0.01; odds ratio (OR) = 2.14, 95% CI = 1.25-3.67, p = 0.01]. EU-Sex also had an increased frequency of U-haplotypes (34.8%) (OR = 2.10, 95% CI = 1.03-4.21, p = 0.01) as well as an increased frequency of CU + UU genotypes (60.9%) compared with HC (38.2%) and EU-Hem (26.6%) (p = 0.043). Distributions of genotypes fitted Hardy-Weinberg equilibrium. Data suggest that V50 homozygosity associates with slow progression and that exon 12 U-haplotypes might be associated with both susceptibility to infection via parenteral route and resistance to infection via sexual exposure. Further studies are required to confirm these findings.

Polymorphisms associated with asthma are inversely related to glioblastoma multiforme

A reduced risk of primary malignant adult brain tumors is observed among people reporting asthma, hay fever, and other allergic conditions; however, findings may be attributed to prediagnostic effects of tumors or recall bias. To determine whether asthma and allergic condition polymorphisms are inversely related to glioblastoma multiforme (GBM) risk, we conducted a population-based case-control study of 111 GBM patients and 422 controls. We identified five single nucleotide polymorphisms on three genes previously associated with asthma [interleukin (IL)-4RA, IL-13, ADAM33] and one gene associated with inflammation (cyclooxygenase-2). Confirming previous literature, we found that self-reported asthma, eczema, and fever are inversely related to GBM [e.g., asthma odds ratio (OR), 0.64; 95% confidence interval (CI), 0.33-1.25]. In addition, IL-4RA Ser478Pro TC, CC, and IL-4RA Gln551Arg AG, AA are positively associated with GBM (OR, 1.64; 95% CI, 1.05-2.55; 1.61; 95% CI, 1.05-2.47), whereas IL-13 -1,112 CT, TT is negatively associated with GBM (0.56; 95% CI, 0.33-0.96). Each of these polymorphism-GBM associations is in the opposite direction of a corresponding polymorphism-asthma association, consistent with previous findings that self-reported asthmatics and people with allergic conditions are less likely to have GBM than are people who do not report these conditions. Because we used germ line polymorphisms as biomarkers of susceptibility to asthma and allergic conditions, our results cannot be attributed to recall bias or effects of GBM on the immune system. However, our findings are also consistent with associations between IL-4RA, IL-13, and GBM that are independent of their role in allergic conditions.

Relationships between specific serum IgE, cytokines and polymorphisms in the IL-4, IL-4Ralpha in patients with penicillins allergy

BACKGROUND

Excessive production of interleukin (IL)-4, IL-13 and interferon (IFN)-gamma is thought to be important in the development of allergic disease and atopy. Several investigators have linked the IL-4 and IL-4R genes to allergic disease and atopy. The aim of this study is to further explore the mechanism of penicillins allergy and evaluate the possible role of the IL-4 C-589T and IL-4RalphaQ576R polymorphisms in modulating the allergic responses to penicillins.

METHODS

Radioallergosorbent test (RAST) was used to detect eight kinds of specific immunoglobulin E (IgE) to penicillins in serum. Serum levels of IL-4, IL-13 and IFN-gamma were measured by using enzyme-linked immunosorbent assay (ELISA). The IL-4 C-589T and IL-4RalphaQ576R polymorphisms were genotyped by polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP).

RESULTS

Compared with control subjects, there were significantly higher levels of IL-4, IL-13 and IFN-gamma in allergic patients with positive specific IgE (P < 0.01), and the lower levels of IL-4 and IFN-gamma were observed in allergic patients with negative specific IgE (P < 0.05). We found a growing trend of IL-4 and IL-13 levels with the kind increasing of positive specific IgE, and even there were significant correlations between the three kinds of cytokines and many kinds of specific IgE (P < 0.05). The IL-4Ralpha*Q576 allele was significantly increased in patients with penicillins allergy compared with control subjects (P < 0.01). Furthermore, the allele was strongly associated with increased serum-specific benzylpenicilloyl (BPO)-, phenoxomethylpenicillanyl (PVA)- or ampicillanyl (APA)-IgE levels in patients with positive specific IgE (P < 0.05).

CONCLUSIONS

These data suggest that IL-4, IL-13 and IFN-gamma play an important roles in penicillins allergy. The IL-4RalphaQ576R polymorphism may involve in the development of penicillins allergy, and through modulating specific serum IgE levels.

Suppressive effect of IL-4 on IL-13-induced genes in mouse lung

Although IL-4 signals through two receptors, IL-4R alpha/common gamma-chain (gamma(c)) and IL-4R alpha/IL-13R alpha1, and only the latter is also activated by IL-13, IL-13 contributes more than IL-4 to goblet cell hyperplasia and airway hyperresponsiveness in murine asthma. To determine whether unique gene induction by IL-13 might contribute to its greater proasthmatic effects, mice were inoculated intratracheally with IL-4 or IL-13, and pulmonary gene induction was compared by gene microarray and real-time PCR. Only the collagen alpha2 type VI (Ca2T6) gene and three small proline-rich protein (SPRR) genes were reproducibly induced > 4-fold more by IL-13 than by IL-4. Preferential IL-13 gene induction was not attributable to B cells, T cells, or differences in cytokine potency. IL-4 signaling through IL-4R alpha/gamma(c) suppresses Ca2T6 and SPRR gene expression in normal mice and induces these genes in RAG2/gamma(c)-deficient mice. Although IL-4, but not IL-13, induces IL-12 and IFN-gamma, which suppress many effects of IL-4, IL-12 suppresses only the Ca2T6 gene, and IL-4-induced IFN-gamma production does not suppress the Ca2T6 or SPRR genes. Thus, IL-4 induces genes in addition to IL-12 that suppress STAT6-mediated SPRR gene induction. These results provide a potential explanation for the dominant role of IL-13 in induction of goblet cell hyperplasia and airway hyperresponsiveness in asthma.

No evidence of association or interaction between the IL4RA, IL4, and IL13 genes in type 1 diabetes

Attempts to identify susceptibility loci that, on their own, have marginal main effects by use of gene-gene interaction tests have increased in popularity. The results obtained from analyses of epistasis are, however, difficult to interpret. Gene-gene interaction, albeit only marginally significant, has recently been reported for the interleukin-4 and interleukin-13 genes (IL4 and IL13) with the interleukin-4 receptor A gene (IL4RA), contributing to the susceptibility of type 1 diabetes (T1D). We aimed to replicate these findings by genotyping both large family and case-control data sets and by using previously published data. Gene-gene interaction tests were performed using linear regression models in cases only. We did not find any single-locus associations with T1D and did not obtain evidence of gene-gene interaction. Additional support from independent samples will be even more important in the study of gene-gene interactions and other subgroup analyses.

An IL-4R alpha allelic variant, I50, acts as a gain-of-function variant relative to V50 for Stat6, but not Th2 differentiation

Signaling through the IL-4R alpha-chain (IL-4Ralpha) is crucial for the development of Th2 cells, central effectors in atopic disease. Alleles of the IL-4Ralpha have been identified that have been variably associated with increased incidence of allergic disease, but there is little direct evidence that any variant is sufficient to alter a target that determines allergic pathophysiology or susceptibility. Variants of IL-4Ralpha encoding isoleucine instead of valine at position 50 (I50 vs V50, respectively) can signal increased Stat6-dependent transcriptional activity, whether in an I50, Q551 or I50, R551 haplotype. Strikingly, signaling through these receptors did not increase the efficiency of Th2 development or the IL-4 mediated repression of Th1 development or a target gene, IL-18Ralpha. Further, IL-4-induced proliferation was similar for Th2 cells independent of the variant expressed. Together these findings indicate that IL-4Ralpha variants that exhibit gain-of-function with respect to Stat6 do not act directly through alterations in Th2/Th1 induction after Ag exposure. The data further suggest that for such variants, any mechanistic involvement is based on a role in cellular targets of Th2 cytokines.

Interleukin-4 receptor signaling pathways in asthma pathogenesis

Asthma is a chronic allergic inflammatory disease, the initiation and progression of which is dependent on the cytokines interleukin (IL)-4 and IL-13 acting through related receptor complexes. Disease pathogenesis is effected by intracellular signaling pathways that couple primarily to specific motifs within the intracellular domain of the IL-4 receptor alpha chain (IL-4Ralpha), a subunit that is common to the IL-4 and IL-13 receptor complexes. Recent studies using genetic approaches have identified distinct functions for the respective IL-4Ralpha-coupled signaling pathways in regulating both early and chronic stages of asthma. Polymorphisms in components of the IL-4 and IL-13 cytokine-receptor axes are associated with allergy and asthma, suggesting that variations among individuals in the activity of this pathway contribute to disease susceptibility and manifestations.

Activation of the IL-4 STAT pathway in rheumatoid synovium

STATs act as second messenger after binding of a signaling molecule to its receptor. IL-4 STAT is directly involved in the IL-4-dependent gene transcription in the nucleus. We examined the expression and activation of IL-4 STAT and its related kinase Jak-1 in rheumatoid synovium. Rheumatoid arthritis (RA) synovial frozen sections of patients with short-term (<1 year) and long-term disease (>2 years) were examined using in situ hybridization and immunohistochemistry. IL-4 STAT mRNA could be detected in synovium of patients with short-term and long-term RA. The most intensive expression of IL-4 STAT mRNA could be seen in follicular inflammatory infiltrates. In the synovial lining, both fibroblasts and macrophages expressed IL-4 STAT mRNA. IL-4 STAT and Jak-1 protein was expressed by synoviocytes, and up-regulation could be induced after stimulation with IL-4. Activation of IL-4 STAT was reflected by phosphorylation of IL-4 STAT. The results indicate that IL-4 STAT is involved in key pathomechanisms in RA synovium and that IL-4 STAT-dependent pathways operate in early and late stages of the disease and presumably contribute to inhibitory immune mechanisms in RA synovium.

The environmental pollutant pyrene induces the production of IL-4

BACKGROUND

Epidemiologic studies and experiments with mouse models suggest that polyaromatic hydrocarbons contained in, among others, diesel exhaust particles can promote the development of allergy.

OBJECTIVE

Because IL-4 organizes allergic responses in vivo, we have investigated whether pyrene, a major compound of diesel exhaust particles, can affect the production of IL-4.

METHODS

IL-4 production by primary human T cells was assessed by ELISA and messenger RNA transcription was detected by Northern blotting. Activation of the IL-4 promoter was tested in reporter gene assays with transiently transfected cell lines.

RESULTS

Pyrene induced transcription of IL-4 messenger RNA and expression of IL-4 protein in primary human T cells. Pyrene, but not related polyaromatic hydrocarbons, enhanced basal transcription of the human and mouse IL-4 promoter.

CONCLUSION

Our results suggest that pyrene may promote allergic diseases by inducing the production of IL-4.

An interleukin-4-induced transcription factor: IL-4 Stat

Interleukin-4 (IL-4) is an immunomodulatory cytokine secreted by activated T lymphocytes, basophils, and mast cells. It plays an important role in modulating the balance of T helper (Th) cell subsets, favoring expansion of the Th2 lineage relative to Th1. Imbalance of these T lymphocyte subsets has been implicated in immunological diseases including allergy, inflammation, and autoimmune disease. IL-4 may mediate its biological effects, at least in part, by activating a tyrosine-phosphorylated DNA binding protein. This protein has now been purified and its encoding gene cloned. Examination of the primary amino acid sequence of this protein indicates that it is a member of the signal transducers and activators of transcription (Stat) family of DNA binding proteins, hereby designated IL-4 Stat. Study of the inhibitory activities of phosphotyrosine-containing peptides derived from the intracellular domain of the IL-4 receptor provided evidence for direct coupling of receptor and transcription factor during the IL-4 Stat activation cycle. Such observations indicate that IL-4 Stat has the same functional domain for both receptor coupling and dimerization.