Genetic deficiencies of both IL-4 receptor alpha chain and IL-10 trigger early onset of severe colitis in mice

Inflammatory bowel diseases are associated with dysregulated inflammatory immune responses in the gastrointestinal tract. We found that deficiencies of both IL-4 receptor alpha chain (IL-4Rα) and IL-10 in BALB/c mice (IL-4Rα × IL-10 KO mice) highly induced spontaneous rectal prolapse and diarrhea. These mice also exhibited severe colitis in their cecum and colon and marked elevation of serum proinflammatory cytokines including TNFα and IFNγ. These pathologies were transmittable with their cecal contents containing Helicobacter spp. Their mesenteric LN cells produced TNFα and IFNγ in response to soluble H. hepaticus antigens and high titers of H. hepaticus-specific serum IgG were also detected. These results suggested the important function of IL-4Rα signaling in controlling the intestinal inflammation and the susceptibility to intestinal microbes including H. hepaticus. Therefore, these IL-4Rα × IL-10 KO mice potentially provide the significant murine model for clarifying the causes and control of spontaneous colitis and intestinal inflammation.

M2a macrophages facilitate resolution of chemically-induced colitis in TLR4-SNP mice

IMPORTANCE

Inflammatory bowel disease (IBD), including Crohn's disease and ulcerative colitis, impacts millions of individuals worldwide and severely impairs the quality of life for patients. Dysregulation of innate immune signaling pathways reduces barrier function and exacerbates disease progression. Macrophage (Mφ) signaling pathways are potential targets for IBD therapies. While multiple treatments are available for IBD, (i) not all patients respond, (ii) responses may diminish over time, and (iii) treatments often have undesirable side effects. Genetic studies have shown that the inheritance of two co-segregating SNPs expressed in the innate immune receptor, TLR4, is associated with human IBD. Mice expressing homologous SNPs ("TLR4-SNP" mice) exhibited more severe colitis than WT mice in a DSS-induced colonic inflammation/repair model. We identified a critical role for M2a "tissue repair" Mφ in the resolution of colitis. Our findings provide insight into potential development of novel therapies targeting Mφ signaling pathways that aim to alleviate the debilitating symptoms experienced by individuals with IBD.

IL-4 receptor alpha blockade dampens allergic inflammation and upregulates IL-17A expression to promote Saureus clearance in antigen sensitized mouse skin

BACKGROUND

Skin colonization with Staphylococcus aureus aggravates atopic dermatitis and exaggerates allergic skin inflammation in mice. IL-4 receptor α (IL-4Rα) blockade is beneficial in atopic dermatitis and reduces Saureus skin colonization through unknown mechanisms. The cytokine IL-17A restrains Saureus growth.

OBJECTIVES

This study sought to examine the effect of IL-4Rα blockade on Saureus colonization at sites of allergic skin inflammation in mice and determine the mechanism involved.

METHODS

BALB/c mice were epicutaneously sensitized with ovalbumin (OVA). Immediately after, PSVue 794-labeled S aureus strain SF8300 or saline was applied and a single dose of anti-IL-4Rα blocking antibody, a mixture of anti-IL-4Rα and anti-IL-17A blocking antibodies, or IgG isotype controls were administered intradermally. Saureus load was assessed 2 days later by in vivo imaging and enumeration of colony forming units. Skin cellular infiltration was examined by flow cytometry and gene expression by quantitative PCR and transcriptome analysis.

RESULTS

IL-4Rα blockade decreased allergic skin inflammation in OVA-sensitized skin, as well as in OVA-sensitized and Saureus-exposed skin, evidenced by significantly decreased epidermal thickening and reduced dermal infiltration by eosinophils and mast cells. This was accompanied by increased cutaneous expression of Il17a and IL-17A-driven antimicrobial genes with no change in Il4 and Il13 expression. IL-4Rα blockade significantly decreased Saureus load in OVA-sensitized and S aureus-exposed skin. IL-17A blockade reversed the beneficial effect of IL-4Rα blockade on Saureus clearance and reduced the cutaneous expression of IL-17A-driven antimicrobial genes.

CONCLUSIONS

IL-4Rα blockade promotes Saureus clearance from sites of allergic skin inflammation in part by enhancing IL-17A expression.

Alpha-linolenic acid improves nasal mucosa epithelial barrier function in allergic rhinitis by arresting CD4+ T cell differentiation via IL-4Rα-JAK2-STAT3 pathway

BACKGROUND

Allergic rhinitis (AR) defined as inflammation and tissue remodeling of the nasal mucosa in atopic individuals after allergen exposure. Alpha-linolenic acid [cis-9, cis-12, cis-15-octadecatrienoic acid (18:3)] (ALA) as dietary supplementation can reduce inflammation and allergic symptoms.

OBJECTIVE

To evaluate the potential therapeutic effect and mechanism of ALA in AR mouse model.

METHODS

Ovalbumin sensitized AR mouse model were challenged with oral ALA administration. Nasal symptoms, tissue pathology, immune cell infiltration and goblet cell hyperplasia were investigated. Levels of IgE, TNF-β, IFN-γ, IL-2, IL-4, IL-5, IL-12, IL-13 and IL-25 were determined by ELISA in serum and nasal fluid. Quantitative RT-PCR and immunofluorescence were performed for occludin and zonula occludens-1 expression. CD3⁺CD4⁺ T-cells from peripheral blood and splenic lymphocytes were isolated and Th1/Th2 ratio were determined. Mouse naive CD4⁺ T cell were isolated and Th1/Th2 ratio, IL-4Rα expression, and IL5/IL13 secretion were determined. IL-4Rα-JAK2-STAT3 pathway change in AR mice were performed by western blot.

RESULTS

Ovalbumin induced AR, nasal symptoms, pathological performance, IgE, and cytokine production. ALA treated mice showed reduced nasal symptoms, nasal inflammation, nasal septum thickening, goblet cell hyperplasia, and eosinophil infiltration. In serum and nasal fluid of ovalbumin challenged mice, ALA decreased IgE, IL-4 levels, and the increase of Th2-cells. ALA prevented the disruption of the epithelial cell barrier in ovalbumin-challenged AR mice. Simultaneously, ALA prevents IL-4 induced barrier disruption. ALA treatment of AR by affecting the differentiation stage of CD4⁺T cells and block IL-4Rα-JAK2-STAT3 pathway.

CONCLUSION

This study suggests that ALA has the potential therapeutic effect to ovalbumin-induced AR. ALA can affect the differentiation stage of CD4⁺T cells and improve epithelial barrier functions through IL-4Rα-JAK2-STAT3 pathways.

CLINICAL IMPLICATION

ALA might be considered as drug candidate for improving epithelial barrier function through Th1/Th2 ratio recovery in AR.

Evidence that oncostatin M synergizes with IL-4 signaling to induce TSLP expression in chronic rhinosinusitis with nasal polyps

BACKGROUND

Oncostatin M (OSM) may promote type 2 inflammation in chronic rhinosinusitis with nasal polyps (CRSwNP) by inducing thymic stromal lymphopoietin (TSLP).

OBJECTIVE

We sought to study the impact of OSM on TSLP synthesis and release from nasal epithelial cells (NECs).

METHODS

OSM receptors, IL-4 receptors (IL-4R), and TSLP were evaluated in mucosal tissue and primary NECs from patients with CRSwNP by quantitative PCR and immunofluorescence. Air-liquid interface-cultured NECs were stimulated with cytokines, including OSM, and quantitative PCR, ELISA, Western blot, and flow cytometry were used to assess the expression of OSM receptors, IL-4R, and TSLP.

RESULTS

Increased levels of OSM receptor β chain (OSMRβ), IL-4Rα, and TSLP were observed in nasal polyp tissues and primary epithelial cells from nasal polyps of patients with CRSwNP compared with control tissues or cells from control subjects. The level of expression of OSMRβ in tissue was correlated with levels of both IL-4Rα and TSLP. OSM stimulation of NECs increased the expression of OSMRβ and IL-4Rα. Stimulation with IL-4 plus OSM augmented the production of TSLP; the response was suppressed by a signal transducer and activator of transcription 6 inhibitor. Stimulation of NECs with IL-4 plus OSM increased the expression of proprotein convertase subtilisin/kexin 3, an enzyme that truncates and activates TSLP.

CONCLUSIONS

OSM increases the expression of IL-4Rα and synergizes with IL-4 to induce the synthesis and release of TSLP in NECs. Because the combination of IL-4 and OSM also augmented the expression of proprotein convertase subtilisin/kexin 3, these results suggest that OSM can induce both synthesis and posttranslational processing/activation of TSLP, promoting type 2 inflammation.

Increased miR-124-3p alleviates type 2 inflammatory response in allergic rhinitis via IL-4Rα

Background and objectives

miRNAs play a crucial role in regulating immune responses. However, the effect of miR-124-3p on type 2 inflammation in allergic rhinitis (AR) is unclear. We aimed to study the immune regulation of miR-124-3p in AR and the mechanisms involved.

Methods

The direct interaction between miR-124-3p and IL-4Rα was confirmed through a dual-luciferase reporter assay. In vitro splenic lymphocytes from mice and peripheral blood mononuclear cells (PBMCs) from healthy individuals were cultured and treated with miR-124-3p mimic/inhibitor. Twenty-four female C57BL/C mice were divided into four groups: control, AR model, miR-124-3p agomir, and miR-124-3p antagomir groups (n = 6 per group). The allergic responses were evaluated based on the number of sneezing and nasal scratching, the serum HDM-specific IgE (sIgE) levels, and the degree of nasal mucosa eosinophil infiltration. The expression of IL-4Rα, p-STAT6, and type 2 inflammatory cytokines (IL-4, IL-5 and IL-13) in lymphocytes or nasal mucosa was determined by qPCR, western blotting, flow cytometry, immunohistochemistry and immunofluorescence.

Results

miR-124-3p directly targets the 3'UTR of IL-4Rα. The miR-124-3p mimic lowered the IL-4Rα, p-STAT6, IL-4, IL-5, and IL-13 expression levels in both mouse splenic lymphocytes and human PBMCs in vitro, and the miR-124-3p inhibitor rescued these changes. Furthermore, the miR-124-3p agomir decreased the levels of IL-4Rα and IL-4 in nasal mucosa, Th2 differentiation in spleen, and allergic response in AR mice. Moreover, the miR-124-3p antagonist increased the IL-4Rα and IL-4 levels and further aggravated the allergic responses.

Conclusions

miR-124-3p might attenuate type 2 inflammation in AR by regulating IL-4Rα signaling, and miR-124-3p may be a promising new target in AR treatment.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00011-022-01614-x.

Rapid and sustained effect of dupilumab on clinical and mechanistic outcomes in aspirin-exacerbated respiratory disease

BACKGROUND

Dupilumab, a mAb targeting IL-4Rα, improves upper and lower airway symptoms in patients with aspirin-exacerbated respiratory disease (AERD), but the mechanisms leading to clinical improvement are not fully elucidated.

OBJECTIVE

Our aim was to identify the mechanistic basis of clinical improvement in patients with AERD treated with dupilumab.

METHODS

A total of 22 patients with AERD were treated with dupilumab for 3 months for severe asthma and/or chronic rhinosinusitis with nasal polyps. Clinical outcomes were assessed at baseline and at 1 and 3 months after initiation of dupilumab. Nasal fluid, urine, blood, and inferior turbinate scrapings were collected at the 3 time points for determination of mediator levels, cellular assays, and RNA sequencing.

RESULTS

Participants had rapid improvement in clinical measures, including sense of smell, sinonasal symptoms, and lung function after 1 month of treatment with dupilumab; the improvements were sustained after 3 months of dupilumab. Baseline severity of smell loss was correlated with lower nasal prostaglandin E₂ levels. Dupilumab increased nasal prostaglandin E₂ level and decreased levels of nasal albumin, nasal and urinary leukotriene E₄, and serum and nasal IgE. Transcripts related to epithelial dysfunction and leukocyte activation and migration were downregulated in inferior turbinate tissue after treatment with dupilumab. There were no dupilumab-induced changes in nasal eosinophilia.

CONCLUSION

Inhibition of IL-4Rα in AERD led to rapid improvement in respiratory symptoms and smell, with a concomitant improvement in epithelial barrier function, a decrease in inflammatory eicosanoid levels, and an increase in the anti-inflammatory eicosanoid prostaglandin E₂ level. The therapeutic effects of dupilumab are likely due to decreased IL-4Rα signaling on respiratory tissue granulocytes, epithelial cells, and B cells.

IL-4/IL-13 axis as therapeutic targets in allergic rhinitis and asthma

Allergic rhinitis (AR) is a common disorder of the upper airway, while asthma is a disease affecting the lower airway and both diseases are usually comorbid. Interleukin (IL)-4 and IL-13 are critical cytokines in the induction of the pathogenic Th2 responses in AR and asthma. Targeting the IL-4/IL-13 axis at various levels of its signaling pathway has emerged as promising targeted therapy in both AR and asthma patient populations. In this review, we discuss the biological characteristics of IL-4 and IL-13, their signaling pathways, and therapeutic antibodies against each cytokine as well as their receptors. In particular, the pleiotropic roles of IL-4 and IL-13 in orchestrating Th2 responses in AR and asthma patients indicate that dual IL-4/IL-13 blockade is a promising therapeutic strategy for both diseases.

IL-4Rα signaling by CD8α+ dendritic cells contributes to cerebral malaria by enhancing inflammatory, Th1, and cytotoxic CD8+ T cell responses

Persistent high levels of proinflammatory and Th1 responses contribute to cerebral malaria (CM). Suppression of inflammatory responses and promotion of Th2 responses prevent pathogenesis. IL-4 commonly promotes Th2 responses and inhibits inflammatory and Th1 responses. Therefore, IL-4 is widely considered as a beneficial cytokine via its Th2-promoting role that is predicted to provide protection against severe malaria by inhibiting inflammatory responses. However, IL-4 may also induce inflammatory responses, as the result of IL-4 action depends on the timing and levels of its production and the tissue environment in which it is produced. Recently, we showed that dendritic cells (DCs) produce IL-4 early during malaria infection in response to a parasite protein and that this IL-4 response may contribute to severe malaria. However, the mechanism by which IL-4 produced by DCs contributing to lethal malaria is unknown. Using Plasmodium berghei ANKA-infected C57BL/6 mice, a CM model, we show here that mice lacking IL-4Rα only in CD8α+ DCs are protected against CM pathogenesis and survive, whereas WT mice develop CM and die. Compared with WT mice, mice lacking IL-4Rα in CD11c+ or CD8α+ DCs showed reduced inflammatory responses leading to decreased Th1 and cytotoxic CD8+ T cell responses, lower infiltration of CD8+ T cells to the brain, and negligible brain pathology. The novel results presented here reveal a paradoxical role of IL-4Rα signaling in CM pathogenesis that promotes CD8α+ DC-mediated inflammatory responses that generate damaging Th1 and cytotoxic CD8+ T cell responses.

Deletion of IL-4Rα signaling on B cells limits hyperresponsiveness depending on antigen load

BACKGROUND

B cells play an important role in allergies through secretion of IgE. IL-4 receptor α (IL-4Rα) is key in allergic asthma and regulates type 2 cytokine production, IgE secretion, and airway hyperresponsiveness. IL-4 activation of B cells is essential for class switching and contributes to the induction of B effector 2 (Be2) cells. The role of Be2 cells and signaling via IL-4Rα in B cells is not clearly defined.

OBJECTIVE

We sought to find out whether IL-4Rα-responsive B cells or Be2 function was essential in experimental allergic asthma.

METHODS

Mice lacking IL-4Rα on B cells (mb1^creIL-4Rα^-/lox) or littermate controls (IL-4Rα^-/lox) and mice lacking IL-4 or IL-4/IL-13 on B cells were sensitized and challenged with high-dose house dust mite (>10 μg) or with low-dose house dust mite (<3 μg). We also adoptively transferred naive IL-4Rα^-/lox or IL-4Rα^-/- B cells into μMT^-/- mice a day before sensitization or a day before challenge. We analyzed lung inflammation, cellular infiltrate, and airway hyperresponsiveness.

RESULTS

We found that IL-4Rα signaling on B cells was important for optimal T_H2 allergic immune responses mainly when the load of antigen is limited. IL-4Rα signaling on B cells was essential for germinal centers and in the effector phase of allergic responses. Be2 cells were essential in airway hyperresponsiveness, but not in other parameters.

CONCLUSIONS

IL-4Rα signaling on B cells is deleterious in allergic asthma because it is required for optimal T_H2 responses, Be2 function, germinal center formation, and T follicular helper cells, especially when the load of the antigen is limiting.

Chronic rhinosinusitis with nasal polyps: mechanistic insights from targeting IL-4 and IL-13 via IL-4Rα inhibition with dupilumab

Introduction: Chronic rhinosinusitis with nasal polyps (CRSwNP) is a complex immunological upper airway disease . CRSwNP, particularly in Caucasians, often has a more distinct T2 inflammatory endotype. IL-4 and IL-13 are key upstream cytokines that help establish and sustain T2 inflammation as well as strongly influencing tissue remodeling. They have a shared signaling receptor IL-4Rα. An attractive and novel therapeutic approach is by way of blocking IL-4 and IL-13 simultaneously via inhibiting IL-4Rα. Dupilumab is a murine derived fully human monoclonal inhibitory antibody directed against IL-4Rα which thereby prevents IL-4/IL-13 cell signaling. Following successful Phase 3 studies dupilumab has become the first licensed biologic for treating CRSwNP. Areas covered: This review covers the essential immunology of CRSwNP in the context of IL-4 and IL-13 signaling via IL-4Rα. The potential mechanisms by which therapeutic improvements occur with dupilumab are evaluated. IL-4, IL-13, dupilumab and rhinosinusitis were used as the search terms in PubMed and Google Scholar through to August 2020. Expert commentary: Dupilumab has the potential to transform the care for patients with CRSwNP. It is essential that further studies are conducted promptly to identify disease-specific biomarkers and clinical traits to guide clinicians on best patient selection thereby ensuring optimal dupilumab outcomes.

Monocyte and Macrophage-Mediated Pathology and Protective Immunity During Schistosomiasis

Infection by Schistosoma parasites culminates in a chronic granulomatous disease characterized by intense tissue fibrosis. Along the course of schistosomiasis, diverse leukocytes are recruited for inflammatory foci. Innate immune cell accumulation in Th2-driven granulomas around Schistosoma eggs is associated with increased collagen deposition, while monocytes and macrophages exert critical roles during this process. Monocytes are recruited to damaged tissues from blood, produce TGF-β and differentiate into monocyte-derived macrophages (MDMs), which become alternatively activated by IL-4/IL-13 signaling via IL-4Rα (AAMs). AAMs are key players of tissue repair and wound healing in response to Schistosoma infection. Alternative activation of macrophages is characterized by the activation of STAT6 that coordinates the transcription of Arg1, Chi3l3, Relma, and Mrc1. In addition to these markers, monocyte-derived AAMs also express Raldh2 and Pdl2. AAMs produce high levels of IL-10 and TGF-β that minimizes tissue damage caused by Schistosoma egg accumulation in tissues. In this review, we provide support to previous findings about the host response to Schistosoma infection reusing public transcriptome data. Importantly, we discuss the role of monocytes and macrophages with emphasis on the mechanisms of alternative macrophage activation during schistosomiasis.

Therapeutic and prophylactic deletion of IL-4Ra-signaling ameliorates established ovalbumin induced allergic asthma

Background

Allergic asthma is a chronic inflammatory airway disease driven predominantly by a T_H2 immune response to environmental allergens. IL‐4Rα‐signaling is essential for driving T_H2‐type immunity to allergens. Anti‐T_H2 therapies have the potential to effectively reduce airway obstruction and inflammation in allergic asthma.

Objective

We investigated potential therapeutic effects of selective inhibition of this pathway in mice with established allergic airway disease. We further investigated whether IL‐4Rα disruption in systemically sensitized mice can prevent the onset of the disease.

Methods

We used Rosa^creERT2IL‐4Rα^−/lox mice, a tamoxifen (TAM)‐inducible IL‐4Rα knockdown model to investigate the role of IL‐4/IL‐13 signaling prior to the onset of the disease and during the effector phase in the ovalbumin‐induced allergic airway disease.

Results

Inducible deletion of IL‐4Rα demonstrated therapeutic effects, on established allergic airway disease, and prevented the development of ovalbumin‐induced airway hyperreactivity, eosinophilia, and goblet cell metaplasia in allergen‐sensitized mice. Interestingly, IL‐4Rα knockdown after allergic sensitization did not induce T_H17, a neutrophilic inflammatory response as observed in global IL‐4Rα‐deficient mice after intranasal allergen challenge.

Conclusion

Abrogation of IL‐4Rα signaling after allergic sensitization would have significant therapeutic benefit for T_H2‐type allergic asthma.

Alternatively activated macrophages are associated with the α2AP production that occurs with the development of dermal fibrosis : The role of alternatively activated macrophages on the development of fibrosis

Background

Fibrotic diseases are characterized by tissue overgrowth, hardening, and/or scarring because of the excessive production, deposition, and contraction of the extracellular matrix (ECM). However, the detailed mechanisms underlying these disorders remain unclear. It was recently reported that α2-antiplasmin (α2AP) is elevated in fibrotic tissue and that it is associated with the development of fibrosis. In the present study, we examined the mechanism underlying the production of α2AP on the development of fibrosis.

Methods

To clarify the mechanism underlying the production of α2AP on the development of fibrosis, we focused on high-mobility group box 1 (HMGB1), which is associated with the development of fibrosis. The mouse model of bleomycin-induced fibrosis was used to evaluate the production of α2AP on the development of fibrosis.

Results

We found that HMGB1 induced the production of α2AP through receptor for advanced glycation end products (RAGE) in fibroblasts. Next, we showed that macrophage reduction by a macrophage-depleting agent, clodronate, attenuated the progression of fibrosis and the production of α2AP and HMGB1 in the bleomycin-induced mice. We also showed that IL-4-stimulated alternatively activated macrophages induced the production of HMGB1, that IL-4-stimulated alternatively activated macrophage conditioned media (CM) induced pro-fibrotic changes and α2AP production, and that the inhibition of HMGB1 and RAGE attenuated these effects in fibroblasts. Furthermore, the blockade of IL-4 signaling by IL-4Rα neutralizing antibodies attenuated the progression of fibrosis and the production of α2AP and HMGB1 in the bleomycin-induced mice.

Conclusion

These findings suggest that alternatively activated macrophage-derived HMGB1 induced the production of α2AP through RAGE and that these effects are associated with the development of fibrosis. Our findings may provide a clinical strategy for managing fibrotic disorders.

Inflammatory Dendritic Cells, Regulated by IL-4 Receptor Alpha Signaling, Control Replication, and Dissemination of Leishmania major in Mice

Leishmaniasis is a vector-borne disease caused by Leishmania parasites. Macrophages are considered the primary parasite host cell, but dendritic cells (DCs) play a critical role in initiating adaptive immunity and controlling Leishmania infection. Accordingly, our previous study in CD11c^creIL-4Rα^−/lox mice, which have impaired IL-4 receptor alpha (IL-4Rα) expression on CD11c⁺ cells including DCs, confirmed a protective role for IL-4/IL-13-responsive DCs in replication and dissemination of parasites during cutaneous leishmaniasis. However, it was unclear which DC subset/s was executing this function. To investigate this, we infected CD11c^creIL-4Rα^−/lox and control mice with L. major GFP⁺ parasites and identified subsets of infected DCs by flow cytometry. Three days after infection, CD11b⁺ DCs and CD103⁺ DCs were the main infected DC subsets in the footpad and draining lymph node, respectively and by 4 weeks post-infection, Ly6C⁺ and Ly6C⁻ CD11b⁺ DCs were the main infected DC populations in both the lymph nodes and footpads. Interestingly, Ly6C⁺CD11b⁺ inflammatory monocyte-derived DCs but not Ly6C⁻CD11b⁺ DCs hosted parasites in the spleen. Importantly, intracellular parasitism was significantly higher in IL-4Rα-deficient DCs. In terms of DC effector function, we found no change in the expression of pattern-recognition receptors (TLR4 and TLR9) nor in expression of the co-stimulatory marker, CD80, but MHCII expression was lower in CD11c^creIL-4Rα^−/lox mice at later time-points compared to the controls. Interestingly, in CD11c^creIL-4Rα^−/lox mice, which have reduced Th1 responses, CD11b⁺ DCs had impaired iNOS production, suggesting that DC IL-4Rα expression and NO production is important for controlling parasite numbers and preventing dissemination. Expression of the alternative activation marker arginase was unchanged in CD11b⁺ DCs in CD11^creIL-4Rα^−/lox mice compared to littermate controls, but RELM-α was upregulated, suggesting IL-4Rα-independent alternative activation. In summary, L. major parasites may use Ly6C⁺CD11b⁺ inflammatory DCs derived from monocytes recruited to infection as “Trojan horses” to migrate to secondary lymphoid organs and peripheral sites, and DC IL-4Rα expression is important for controlling infection.

IL-13 and IL-4, but not IL-5 nor IL-17A, induce hyperresponsiveness in isolated human small airways

BACKGROUND

Specific inflammatory pathways are indicated to contribute to severe asthma, but their individual involvement in the development of airway hyperresponsiveness remains unexplored.

OBJECTIVE

This experimental study in human small bronchi aimed to provide insight into which of the type 2 and type 17 cytokines cause hyperresponsiveness of airway smooth muscle.

METHODS

Explanted small bronchi isolated from human lung tissue and human airway smooth muscle cells were treated for 2 and 1 day(s), respectively, with 100 ng/mL of IL-4, IL-5, IL-13, or IL-17A, and contractile responses, Ca²⁺ mobilization, and receptor expression were assessed.

RESULTS

Treatment with IL-13 increased the potency of histamine, carbachol, and leukotriene D₄ as contractile agonists. IL-4, but not IL-5 or IL-17A, also increased the potency of histamine. In human airway smooth muscle cells, IL-13 and IL-4, but not IL-5 and IL-17A, enhanced the histamine-induced Ca²⁺ mobilization that was accompanied with increased mRNA expression of histamine H₁ and cysteinyl leukotriene CysLT₁ receptors. RNA sequencing of isolated bronchi confirmed the IL-13-mediated upregulation of H₁ and CysLT₁ receptors, without showing an alteration of muscarinic M₃ receptors. Dexamethasone had no effects on IL-13-induced hyperresponsiveness in human bronchi, the increased Ca²⁺ mobilization, or the enhanced receptor expression. In contrast, antagonism of the common receptor for IL-13 and IL-4 by the biologic dupilumab prevented the effects of both IL-13 and IL-4 in human bronchi and human airway smooth muscle cells.

CONCLUSIONS

The glucocorticoid-insensitive hyperrresponsiveness in isolated human airways induced by IL-13 and IL-4 provides further evidence that the IL-4Rα pathway should be targeted as a new strategy for the treatment of airway hyperresponsiveness in asthma.

Deletion of Chitinase-3-like 1 accelerates stroke development through enhancement of Neuroinflammation by STAT6-dependent M2 microglial inactivation in Chitinase-3-like 1 knockout mice

Chitinase 3-like 1 (Chi3L1) plays a major role in the pathogenesis of inflammatory diseases. We investigated the effect of Chi3L1 knockout on stroke development. Ischemia/reperfusion was induced by middle cerebral artery occlusion (MCAO) in Chi3L1 knockout and wildtype mice. Significantly increased infarct volume and decreased neurological deficit scores at 24 h after ischemia/reperfusion were found in Chi3L1 knockout mice compared to wildtype mice. Moreover, ischemic neuronal cell death was increased in Chi3L1 knockout mice through increased oxidative stress and release of IL-6 and IL-1β but IL-10 and IL-4 were reduced. Furthermore, expression of inflammation-related proteins (iNOS, COX-2, Iba-1, and GFAP) was significantly increased in Chi3L1 knockout mice compared to wildtype. In microglia isolated from MCAO-injured Chi3L1 knockout mice, expression of M1 markers (iNOS, CD86, IL-1β, and IL-6) was increased and M2 markers (Arg1, Mrc1, IL-10, and IL-4Ra) was decreased. In BV-2 cells, knockdown of Chi3L1 increased TNF-α- and INF-γ-induced expression of iNOS, COX-2, and Iba-1, but decreased the expression of Arg1, MRC1, and IL-4 receptor-alpha (IL-4Rα). Expression of IL-4Rα, an important factor of M2 polarization, and its downstream signals p-JAK1, p-JAK3, and p-STAT6, was much reduced in the knockout mice. Additionally, in BV-2 cells, knockdown of Chi3L1 by siRNA Chi3L1 decreased rhTNF-α- and INF-γ-induced expression of IL-4Rα, p-JAK1, p-JAK3, and p-STAT6. Furthermore, treatment with AS1517499 abolished Chi3L1 knockdown-induced reduced IL-4Rα and Arg1 but not CD86 expression. Our results indicate that deletion of Chi3L1 accelerates stroke development through enhancement of neuroinflammation by markedly decreasing STAT6-dependent M2 macrophage polarization.

IL-4 Mediated Resistance of BALB/c Mice to Visceral Leishmaniasis Is Independent of IL-4Rα Signaling via T Cells

Previous studies infecting global IL-4Rα^−/−, IL-4^−/−, and IL-13^−/−mice on a BALB/c background with the visceralizing parasite Leishmania donovani have shown that the T helper 2 cytokines, IL-4, and IL-13, play influential but not completely overlapping roles in controlling primary infection. Subsequently, using macrophage/neutrophil-specific IL-4Rα deficient BALB/c mice, we demonstrated that macrophage/neutrophil unresponsiveness to IL-4 and IL-13 did not have a detrimental effect during L. donovani infection. Here we expand on these findings and show that CD4⁺ T cell-(Lck^cre), as well as pan T cell-(iLck^cre) specific IL-4Rα deficient mice, on a BALB/c background, unlike global IL-4Rα deficient mice, are also not adversely affected in terms of resistance to primary infection with L. donovani. Our analysis suggested only a transient and tissue specific impact on disease course due to lack of IL-4Rα on T cells, limited to a reduced hepatic parasite burden at day 30 post-infection. Consequently, the protective role(s) demonstrated for IL-4 and IL-13 during L. donovani infection are mediated by IL-4Rα-responsive cell(s) other than macrophages, neutrophils and T cells.

Scratching Counteracts IL-13 Signaling by Upregulating the Decoy Receptor IL-13Rα2 in Keratinocytes

The vicious itch–scratch cycle is a cardinal feature of atopic dermatitis (AD), in which IL-13 signaling plays a dominant role. Keratinocytes express two receptors: The heterodimeric IL-4Rα/IL-13Rα1 and IL-13Rα2. The former one transduces a functional IL-13 signal, whereas the latter IL-13Rα2 works as a nonfunctional decoy receptor. To examine whether scratch injury affects the expression of IL-4Rα, IL-13Rα1, and IL-13Rα2, we scratched confluent keratinocyte sheets and examined the expression of three IL-13 receptors using quantitative real-time PCR (qRT-PCR) and immunofluorescence techniques. Scratch injuries significantly upregulated the expression of IL13RA2 in a scratch line number-dependent manner. Scratch-induced IL13RA2 upregulation was synergistically enhanced in the simultaneous presence of IL-13. In contrast, scratch injuries did not alter the expression of IL4R and IL13RA1, even in the presence of IL-13. Scratch-induced IL13RA2 expression was dependent on ERK1/2 and p38 MAPK signals. The expression of IL-13Rα2 protein was indeed augmented in the scratch edge area and was also overexpressed in lichenified lesional AD skin. IL-13 inhibited the expression of involucrin, an important epidermal terminal differentiation molecule. IL-13-mediated downregulation of involucrin was attenuated in IL-13Rα2-overexpressed keratinocytes, confirming the decoy function of IL-13Rα2. Our findings indicate that scratching upregulates the expression of the IL-13 decoy receptor IL-13Rα2 and counteracts IL-13 signaling.

Important roles of CD32 in promoting suppression of IL-4 induced immune responses by a novel anti-IL-4Rα therapeutic antibody

Asthma is characterized by airway hyperresponsiveness and inflammation, as well as underlying structural changes to the airways. Interleukin-4 (IL-4) is a key T-helper type 2 (Th2) cytokine that plays important roles in the pathogenesis of atopic and eosinophilic asthma. We developed a novel humanized anti-IL-4Rα antibody that can potently inhibit IL-4/IL-13-mediated TF-1 cell proliferation. Using monocytes isolated from human peripheral blood mononuclear cells (PBMCs), we revealed a critical role of CD32 in modulating the immune responses of monocytes in response to blockade of IL-4Rα signaling pathway. We, therefore, devised a new strategy to increase the efficacy of the anti-IL-4Rα monoclonal antibody for the treatment of asthma and other atopic diseases by co-engaging CD32 and IL-4Rα on monocytic cells by choosing IgG classes or Fc mutations with higher affinities for CD32. The antibody with selectively enhanced affinity for CD32A displayed superior suppression of IL-4-induced monocytes’ activities, including the down-regulation of CD23 expression. Intriguingly, further analysis demonstrated that both CD32A and CD32B contributed to the enhancement of antibody-mediated suppression of CD23 expression from monocytes in response to blockade of IL-4Rα signaling. Furthermore, inhibition of IgE secretion from human PBMC by the antibody variants further suggests that the complex allergic inflammation mediated by IL-4/IL-4Rα signaling might result from a global network where multiple cell types that express multiple FcγRs are all involved, of which CD32, especially CD32A, is a key mediator. In this respect, our study provides new insights into designing therapeutic antibodies for targeting Th2 cytokine-mediated allergic pathogenesis.

IL-4Rα-expressing CD11c+ cells contribute to driving optimal cellular responses during Schistosoma mansoni infection in mice

Development of IL‐4 receptor alpha (IL‐4Rα)‐dependent cellular immunity regulates host protection against acute schistosomiasis. In this study, we investigated the importance of IL‐4Rα‐expressing CD11c⁺ cells in driving the development of optimal cellular responses to Schistosoma mansoni infection by using CD11c^creIL‐4Rα^−/lox BALB/c mice, which lacked IL‐4Rα expression on dendritic cells and alveolar macrophages. Abrogation of IL‐4Rα expression on CD11c⁺ cells affected activation of CD4⁺ T cells, resulting in reduced numbers of effector CD4⁺ T cells and impaired production of Th1 and Th2 cytokines by CD4⁺ T cells ex vivo. However, secretion of both type 1 and type 2 Ab isotypes was unchanged in infected CD11c‐specific IL‐4Rα‐deficient mice compared to littermate controls. Together, these data demonstrate that IL‐4Rα‐expressing CD11c⁺ cells play an important role in maintaining cellular immunity during schistosomiasis in mice.

IL-4Rα Signaling in Keratinocytes and Early IL-4 Production Are Dispensable for Generating a Curative T Helper 1 Response in Leishmania major-Infected C57BL/6 Mice

Experimental infection with the protozoan parasite Leishmania major has been extensively used to understand the mechanisms involved in T helper cell differentiation. Following infection, C57BL/6 mice develop a small self-healing cutaneous lesion and they are able to control parasite burden, a process linked to the development of T helper (Th) 1 cells. The local presence of IL-12 has been reported to be critical in driving Th1 cell differentiation. In addition, the early secretion of IL-4 was reported to potentially contribute to Th1 cell differentiation. Following infection with L. major, early keratinocyte-derived IL-4 was suggested to contribute to Th1 cell differentiation. To investigate a putative autocrine role of IL-4 signaling on keratinocytes at the site of infection, we generated C57BL/6 mice deficient for IL-4Rα expression selectively in keratinocytes. Upon infection with L. major, these mice could control their inflammatory lesion and parasite load correlating with the development of Th1 effector cells. These data demonstrate that IL-4 signaling on keratinocytes does not contribute to Th1 cell differentiation. To further investigate the source of IL-4 in the skin during the first days after L. major infection, we used C57BL/6 IL-4 reporter mice allowing the visualization of IL-4 mRNA expression and protein production. These mice were infected with L. major. During the first 3 days after infection, skin IL-4 mRNA expression was observed selectively in mast cells. However, no IL-4 protein production was detectable locally. In addition, early IL-4 blockade locally had no impact on subsequent Th1 cell differentiation and control of the disease. Taken together, the present data rule out a major role for skin IL-4 and keratinocyte IL-4Rα signaling in the development of a Th1 protective immune response following experimental infection with L. major.

Sensory Neurons Co-opt Classical Immune Signaling Pathways to Mediate Chronic Itch

Mammals have evolved neurophysiologic reflexes, such as coughing and scratching, to expel invading pathogens and noxious environmental stimuli. It is well established that these responses are also associated with chronic inflammatory diseases, including asthma and atopic dermatitis. However, the mechanisms by which inflammatory pathways promote sensations such as itch remain poorly understood. Here, we show that type 2 cytokines directly activate sensory neurons in both mice and humans. Further, we demonstrate that chronic itch is dependent on neuronal IL-4Rα and JAK1 signaling. We also observe that patients with recalcitrant chronic itch that failed other immunosuppressive therapies markedly improve when treated with JAK inhibitors. Thus, signaling mechanisms previously ascribed to the immune system may represent novel therapeutic targets within the nervous system. Collectively, this study reveals an evolutionarily conserved paradigm in which the sensory nervous system employs classical immune signaling pathways to influence mammalian behavior.

Defective IL-4 signaling in T cells defines severe common variable immunodeficiency

Common variable immunodeficiency (CVID) is defined by hypogammaglobulinemia and B-cell dysfunction, with significant clinical and immunological heterogeneity. Severe non-infectious complications, such as autoimmunity, granulomatous disease and splenomegaly, constitute a major cause of morbidity in CVID patients. T cells are generally regarded important for development of these clinical features. However, while T-cell abnormalities have been found in CVID patients, functional characteristics of T cells corresponding to well-defined clinical subtypes have not been identified. As common γ-chain cytokines play important roles in survival and differentiation of T cells, characterization of their signaling pathways could reveal functional differences of clinical relevance. We characterized CVID T cells functionally by studies of cytokine-induced signaling, and correlated the findings to defined clinical subtypes. Peripheral blood T cells from 29 CVID patients and 19 healthy donors were analyzed for i) phenotype, ii) cytokine-induced (interleukin (IL)-2, IL-4, IL-7 and IL-21) phosphorylation of signal transducer and activator of transcription (STAT) 3, STAT5 and STAT6, and iii) T-helper (Th)1/Th2 polarization. Expression of IL-4 receptor and downstream signaling molecules was measured. A subgroup of CVID patients (n = 7) was identified by impaired IL-4-induced p-STAT6 in naive and memory CD4 and CD8 T cells. This corresponded to patients with the largest accumulation of severe (non-infectious) complications. The signaling defect persisted over years and was not due to constitutively activated p-STAT6. The CD4 T cells were strongly Th1-skewed, but IL-4 signaling was impaired independently of Th status. However, IL-4Rα and Janus kinase (JAK) 1 mRNA levels were significantly lower than in normal donors, providing a likely mechanism for the defective IL-4-induced p-STAT6 and Th1-bias. In conclusion, we identified a subgroup of CVID patients with defective IL-4 signaling in T cells, with severe clinical features of inflammation and autoimmunity.

IL-4Rα aptamer-liposome-CpG oligodeoxynucleotides suppress tumour growth by targeting the tumour microenvironment

Tumour immunosuppressive microenvironments inhibit antigen-specific cellular responses and interfere with CpG-mediated immunotherapy. Overcoming tumour microenvironment (TME) immunosuppression is an important strategy for effective therapy. This study investigated the ability of a tumour-targeting IL-4Rα aptamer-liposome-CpG ODN delivery system to introduce CpG into tumours and overcome the immunosuppressive TME. The IL-4Rα-liposome-CpG delivery system was prepared. FAM-CpG visualisation was used to demonstrate tumour targeting in vitro and in vivo. Anti-tumour effects of this delivery system were evaluated in CT26 tumour-bearing mice. Mechanisms for conquering the TME were investigated. FAM-CpG was better distributed into the tumours upon treatment with IL-4Rα-liposome-FAM-CpG compared to distribution in the control group in vitro and in vivo. IL-4Rα-aptamer-liposome-CpG treatment inhibited distinct myeloid-derived suppressor cell populations in tumours and bone marrow. Similar profiles were observed for regulatory T cells in tumours. In CT26 tumour-bearing mice, IL-4Rα-liposome-CpG treatment exhibited enhanced anti-tumour activity. Increased mRNA levels of TNF-α, IL-2, and IL-12, and decreased mRNA levels of VEGF, IL-6, IL-10, MMP9, arginase-1, inducible NOS, CXCL9, p-Stat3, and NF-κB were observed in tumours upon IL-4R-liposome-CpG-treatment. The results suggested that pharmacologic targeting by the IL-4R aptamer-liposome-CpG system improves TME therapeutic benefit and provides a rationale for cancer immunotherapies.

Drug evaluation review: dupilumab in atopic dermatitis

Atopic dermatitis (AD) is characterized by type 2 helper T (Th2) cell-driven inflammation. Dupilumab is a fully human monoclonal antibody directed against the IL-4 receptor α subunit that blocks the signaling of IL-4 and IL-13, both key cytokines in Th2-mediated pathways. In Phase I and II studies of adults with moderate-to-severe AD, dupilumab administered as monotherapy or with topical corticosteroids resulted in rapid, significant improvements in clinical efficacy, patient-reported outcomes, and Th2-related serum and tissue biomarkers, and shifted the RNA expression profile of lesional skin to a more nonlesional signature. In all clinical studies to date, dupilumab has shown a favorable safety profile with no dose-limiting toxicity. The robust effects of dupilumab on skin inflammation and pruritus confirm the pathogenic role of IL-4 and IL-13 signaling in adult AD, and further support the application of Th2 cytokine antagonists in the treatment of this disease.

Gene Polymorphism of Interleukin-4, Interleukin-4 Receptor and STAT6 in Children with Atopic Dermatitis in Taif, Saudi Arabia

AIM OF STUDY

This work was performed to evaluate the level of IL-4, and to clarify the role of IL-4 gene polymorphism at position cytosine -590-to-thyamine (C-590T), IL-4Rα gene polymorphism at position adenine +4679-to-guanine (A+4679G) [isoleucine-50-valine (I50V)] and STAT6 gene polymorphism at position guanine 2964-to-adenine (G2964A) in Saudi children with non-atopic dermatitis (non-AD) and atopic dermatitis (AD) to identify their role in the pathogenesis of these diseases.

SUBJECTS AND METHODS

This study included 150 children: 50 healthy children as controls, 50 with non-AD, and 50 with AD. They were subjected to full clinical examination, complete blood picture, skin prick test, and determination of serum interleukin-4 (IL-4) and total immunoglobulin-E (IgE) levels. Detection of interleukin-4 gene (C-590T), interleukin-4 receptor alpha gene (A+4679G) (I50V), and STAT6 gene (G2964A) polymorphisms were performed by PCR-based restriction fragment length polymorphism (PCR-RFLP).

RESULTS

There was a significant (P < 0.01) association between genotype and allele frequencies of IL-4Rα (A+4679G) (I50V) polymorphism in the AD group (but not non-AD group). Moreover, there was a significant association between genotype and allele frequencies of the STAT6 (G2946A) polymorphism in the non-AD (P < 0.05) and AD (P < 0.01) groups. On the other hand, there was no significant association between genotype and allele frequencies of the (C-590T) polymorphism in the non-AD group and AD group. There was a significant (P < 0.001) higher total IgE level in patients compared to the controls. Moreover, the mean values of total IgE were significantly different among the different allelic variants of (C-590T), (I50V), (G2964A) polymorphisms of IL-4, IL-4Rα, and STAT6 genes, respectively, in all the studied groups. On the other hand, there was no significant difference of serum IL-4 levels among all the studied patients, or among the different allelic variants of (C-590T), (I50V), (G2964A) polymorphisms of IL-4, IL-4Rα, and STAT6 genes, respectively.

CONCLUSION

IL-4Rα gene (I50V) and STAT6 gene (G2964) polymorphisms may play a role in development of eczema; however, the IL-4 gene polymorphism (C-590T) had no relationship with susceptibility to the disease among Saudi children.

Role of IL-4Rα during acute schistosomiasis in mice

Schistosomiasis is an important parasitic disease that causes major host morbidity and mortality in endemic areas. Research conducted in mouse models of schistosomiasis has provided great insights and understanding of how host protective immunity is orchestrated and key cellular populations involved in this process. Earlier studies using cytokine-deficient mice demonstrated the importance of IL-4 and IL-10 in mediating host survival during acute schistosomiasis. Subsequent studies employing transgenic mice carrying cell-specific deletion of IL-4Rα generated using the Cre/LoxP recombination system have been instrumental in providing more in-depth understanding of the mechanisms conferring host resistance to Schistosoma mansoni infection. In this review, we will summarize the contributions of IL-4/IL-13-responsive cellular populations in host resistance during acute schistosomiasis and their role in limiting tissue pathology.

Interleukin-4 receptor alpha overexpression in human bladder cancer correlates with the pathological grade and stage of the disease

Previously, we have demonstrated that interleukin-4 receptor α (IL-4Rα) is overexpressed on a variety of human cancers and can serve as target for IL-4 immunotoxin comprised of IL-4 and a mutated Pseudomonas exotoxin. However, its expression and association with grade and clinical stage of bladder cancer has not been studied. IL-4Rα expression was examined in human bladder cancer cell lines, mouse xenografts, and biopsy specimens at mRNA and protein levels by real-time RT-PCR and IHC/ISH techniques. We also examined the effect of IL-4 on proliferation and invasion of bladder carcinoma cell lines. For tissue microarray (TMA) results, we analyzed the precision data using exact binomial proportion with exact two-sided P-values. We used Cochran–Armitage Statistics with exact two-sided P-values to examine the trend analysis of IL-4Rα over grade or stage of the bladder cancer specimens. The influence of age and gender covariates was also analyzed using multiple logistic regression models. IL-4Rα is overexpressed in five bladder cancer cell lines, while normal bladder and human umbilical vein cell lines (HUVEC) expressed at low levels. Two other chains of IL-4 receptor complex, IL-2RγC and IL-13Rα1, were absent or weakly expressed. IL-4 modestly inhibited the cell proliferation, but enhanced cell invasion of bladder cancer cell lines in a concentration-dependent manner. Bladder cancer xenografts in immunodeficient mice also maintained IL-4Rα overexpression in vivo. Analysis of tumor biopsy specimens in TMAs revealed significantly higher IL-4Rα immunostaining (≥2+) in Grade 2 (85%) and Grade 3 (97%) compared to Grade 1 tumors (0%) (P ≤ 0.0001). Similarly, 9% stage I tumors were positive for IL-4Rα (≥2+) compared to 84% stage II (P ≤ 0.0001) and 100% stages III–IV tumors (P ≤ 0.0001). IL-13Rα1 was also expressed in tumor tissues but at low levels and it did not show any correlation with the grade and stage of disease. However, the IL-2RγC was not expressed. Ten normal bladder specimens demonstrated ≤1+ staining for IL-4Rα and IL-13Rα1 and no staining for IL-2RγC. These results demonstrate that IL-4Rα is overexpressed in human bladder cancer, which correlates with advanced grade and stage of the disease. Thus, IL-4Rα may be a bladder tumor-associated protein and a prognostic biomarker.

Host protective roles of type 2 immunity: parasite killing and tissue repair, flip sides of the same coin

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Type 2 immunity is associated with both helminth infection and responses to injury.

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Pathways involved in tissue repair and helminth immunity overlap.

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The IL-4Rα is central to accelerating both repair and helminth control.

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Adaptive immunity contributes to more rapid wound repair.

Metazoan parasites typically induce a type 2 immune response, characterized by T helper 2 (Th2) cells that produce the cytokines IL-4, IL-5 and IL-13 among others. The type 2 response is host protective, reducing the number of parasites either through direct killing in the tissues, or expulsion from the intestine. Type 2 immunity also protects the host against damage mediated by these large extracellular parasites as they migrate through the body. At the center of both the innate and adaptive type 2 immune response, is the IL-4Rα that mediates many of the key effector functions. Here we highlight the striking overlap between the molecules, cells and pathways that mediate both parasite control and tissue repair. We have proposed that adaptive Th2 immunity evolved out of our innate repair pathways to mediate both accelerated repair and parasite control in the face of continual assault from multicellular pathogens. Type 2 cytokines are involved in many aspects of mammalian physiology independent of helminth infection. Therefore understanding the evolutionary relationship between helminth killing and tissue repair should provide new insight into immune mechanisms of tissue protection in the face of physical injury.

Association between genes encoding components of the IL-4/IL-4 receptor pathway and dermatitis in children

OBJECTIVE

To determine whether IL-4, IL-4Rα and STAT6 polymorphisms are associated with susceptibility to dermatitis in Egyptian children.

METHODS

We genotyped three groups of children, consisting of 106 atopic dermatitis (AD) children, 95 non-AD children, and 100 of healthy controls, for IL-4 (-590 C/T), (-33 C/T), IL-4Rα (I50V), (Q576R) and STAT6 (2964 G/A), (2892 C/T) gene polymorphisms using PCR-RFLP assay. Total serum IgE and serum IL-4 levels were detected by ELISA.

RESULTS

There was a non-significant association of IL-4 -590 C/T, -33 C/T polymorphisms in the children with non-AD or those with AD when compared with the controls. We identified a significant association between IL-4Rα I50V, Q576R polymorphisms and dermatitis susceptibility in AD (p=0.002, <0.001 respectively), whereas no such association was observed in non-AD group (p=0.52, 0.99 respectively). A significant association between STAT6 polymorphisms and both types of dermatitis was found. Patients who were carriers of IL4 -590C, IL-4Rα I50V G, STAT6 2964 A and STAT6 2892 T had an increased risk of AD [OR and 95% CI: 3.2 (2.5-4.2), p=0.005]. Furthermore, there was no relation between each polymorphism and serum IL-4 level (p>0.05 for each) while homozygosity for the risk alleles of IL-4, IL-4Rα and STAT6 SNPs were significantly associated with increased total IgE levels in all subjects.

CONCLUSION

In Egyptian children, the IL-4Rα and the STAT6 polymorphism may play a role in susceptibility to AD. In addition, gene-gene interaction between the IL-4, the IL-4Rα and the STAT6 significantly increases an individual's susceptibility to AD.

IL-13 receptor α2 contributes to development of experimental allergic asthma

BACKGROUND

IL-13 receptor α2 (IL-13Rα2) binds IL-13 with high affinity and modulates IL-13 responses. There are soluble and membrane forms of IL-13Rα2 generated by alternative splicing in mice, but human subjects express only the membrane form of IL-13Rα2 (memIL-13Rα2).

OBJECTIVE

We determined the role of memIL-13Rα2 in the development of allergic inflammation in mouse models of asthma.

METHODS

IL-13Rα2-deficient and memIL-13Rα2 lung epithelium-specific transgenic mice were challenged with house dust mite (HDM). Airway hyperresponsiveness (AHR) and inflammation were assessed based on the airway pressure-time index, bronchoalveolar lavage (BAL) cell counts, and lung histology. Mucus production was determined by means of periodic acid-Schiff staining of lung sections, Western blot analysis of chloride channel calcium activated 3 (CLCA3) expression in lung homogenates, and ELISA of Muc5ac in BAL fluid. The expression of cytokines and chemokines was determined by using RT-quantitative PCR.

RESULTS

In IL-13Rα2-deficient mice AHR and airway inflammation were attenuated compared with levels seen in wild-type mice after HDM challenge. Lung epithelial overexpression of memIL-13Rα2 in the IL-13Rα2-deficient mice reconstituted AHR and inflammation to levels similar to those observed in HDM-challenged wild-type mice. Mucus production was attenuated in lungs from HDM-treated IL-13Rα2-deficient mice, whereas lung epithelial overexpression of memIL-13Rα2 increased mucus production. Lung epithelial overexpression of memIL-13Rα2 had no effect on levels of the soluble form of IL-13Rα2 in serum or BAL fluid and did not affect IL-13-dependent signal transducer and activator of transcription 6 activation in the lungs.

CONCLUSION

These data collectively support a distinct role for memIL-13Rα2 in the lung and suggest that memIL-13Rα2 might contribute to allergic inflammation.