Efficacy and Safety of Itepekimab in Patients with Moderate-to-Severe Asthma.

BACKGROUND: Monoclonal antibodies targeting IgE, interleukin-4 and -13, and interleukin-5 are effective in treating severe type 2 asthma, but new targets are needed. Itepekimab is a new monoclonal antibody against the upstream alarmin interleukin-33. The efficacy and safety of itepekimab as monotherapy, as well as in combination with dupilumab, in patients with asthma are unclear. METHODS: In a phase 2 trial, we randomly assigned, in a 1:1:1:1 ratio, adults with moderate-to-severe asthma receiving inhaled glucocorticoids plus long-acting beta-agonists (LABAs) to receive subcutaneous itepekimab (at a dose of 300 mg), itepekimab plus dupilumab (both at 300 mg; combination therapy), dupilumab (300 mg), or placebo every 2 weeks for 12 weeks. After randomization, LABA was discontinued at week 4, and inhaled glucocorticoids were tapered over weeks 6 through 9. The primary end point was an event indicating a loss of asthma control, assessed in the itepekimab group and the combination group, as compared with the placebo group. Secondary and other end points included lung function, asthma control, quality of life, type 2 biomarkers, and safety. RESULTS: A total of 296 patients underwent randomization. By 12 weeks, an event indicating a loss of asthma control occurred in 22% of the patients in the itepekimab group, 27% of those in the combination group, and 19% of those in the dupilumab group, as compared with 41% of those in the placebo group; the corresponding odds ratios as compared with placebo were as follows: in the itepekimab group, 0.42 (95% confidence interval [CI], 0.20 to 0.88; P = 0.02); in the combination group, 0.52 (95% CI, 0.26 to 1.06; P = 0.07); and in the dupilumab group, 0.33 (95% CI, 0.15 to 0.70). As compared with placebo, the forced expiratory volume in 1 second before bronchodilator use increased with the itepekimab and dupilumab monotherapies but not with the combination therapy. Itepekimab treatment improved asthma control and quality of life, as compared with placebo, and led to a greater reduction in the mean blood eosinophil count. The incidence of adverse events was similar in all four trial groups. CONCLUSIONS: Interleukin-33 blockade with itepekimab led to a lower incidence of events indicating a loss of asthma control than placebo and improved lung function in patients with moderate-to-severe asthma. (Funded by Sanofi and Regeneron Pharmaceuticals; ClinicalTrials.gov number, NCT03387852.).

Rational Design, Synthesis and Evaluation of Oxazolo[4,5-c]-quinolinone Analogs as Novel Interleukin-33 Inhibitors.

Interleukin-33 (IL-33) is an epithelial-derived cytokine that plays an important role in immune-mediated diseases such as asthma, atopic dermatitis, and rheumatoid arthritis. Although IL-33 is considered a potential target for the treatment of allergy-related diseases, no small molecule that inhibits IL-33 has been reported. Based on the structure-activity relationship and in vitro 2D NMR studies employing 15 N-labeled IL-33, we identified that the oxazolo[4,5-c]-quinolinone analog 7 c binds to the interface region of IL-33 and IL-33 receptor (ST2), an orphan receptor of the IL-1 receptor family. Compound 7 c effectively inhibited the production of IL-6 in human mast cells in a dose-dependent manner. Compound 7 c is the first low molecular weight IL-33 inhibitor and may be used as a prototype molecule for structural optimization and investigation of the IL-33/ST2 signaling pathway.

New Biologics for the Treatment of Atopic Dermatitis: Analysis of Efficacy, Safety, and Paradoxical Atopic Dermatitis Acceleration.

Atopic dermatitis (AD) is a chronic, inflammatory skin disease with an eczematous rash and itching. Due to undesired adverse effects of traditional systemic treatment, there is still an unmet need for safe and effective long-term therapy for refractory AD. As our understanding of the pathogenesis underlying AD grows, novel treatments targeting specific molecules have been developed. Here, we discuss the efficacy and safety profiles of these drugs in recent clinical trials. Among their adverse effects, of particular note is AD acceleration. Although there is still debate about whether certain adverse reactions can be said to be paradoxical adverse events (PAEs), a wide range of PAEs have been reported during biological treatment for chronic immune-mediated diseases. Close surveillance of novel biologics is crucial to detect new undescribed paradoxical reactions and to shed light on the convoluted pathogenesis of AD.

ATP/IL-33-triggered hyperactivation of mast cells results in an amplified production of pro-inflammatory cytokines and eicosanoids.

IL-33 and ATP are alarmins, which are released upon damage of cellular barriers or are actively secreted upon cell stress. Due to high-density expression of the IL-33 receptor T1/ST2 (IL-33R), and the ATP receptor P2X7, mast cells (MCs) are one of the first highly sensitive sentinels recognizing released IL-33 or ATP in damaged peripheral tissues. Whereas IL-33 induces the MyD88-dependent activation of the TAK1-IKK2-NF-κB signalling, ATP induces the Ca2+ -dependent activation of NFAT. Thereby, each signal alone only induces a moderate production of pro-inflammatory cytokines and lipid mediators (LMs). However, MCs, which simultaneously sense (co-sensing) IL-33 and ATP, display an enhanced and prolonged activation of the TAK1-IKK2-NF-κB signalling pathway. This resulted in a massive production of pro-inflammatory cytokines such as IL-2, IL-4, IL-6 and GM-CSF as well as of arachidonic acid-derived cyclooxygenase (COX)-mediated pro-inflammatory prostaglandins (PGs) and thromboxanes (TXs), hallmarks of strong MC activation. Collectively, these data show that co-sensing of ATP and IL-33 results in hyperactivation of MCs, which resembles to MC activation induced by IgE-mediated crosslinking of the FcεRI. Therefore, the IL-33/IL-33R and/or the ATP/P2X7 signalling axis are attractive targets for therapeutical intervention of diseases associated with the loss of integrity of cellular barriers such as allergic and infectious respiratory reactions.

Astegolimab (anti-ST2) efficacy and safety in adults with severe asthma: A randomized clinical trial.

BACKGROUND: The IL-33/ST2 pathway is linked with asthma susceptibility. Inhaled allergens, pollutants, and respiratory viruses, which trigger asthma exacerbations, induce release of IL-33, an epithelial-derived "alarmin." Astegolimab, a human IgG2 mAb, selectively inhibits the IL-33 receptor, ST2. Approved biologic therapies for severe asthma mainly benefit patients with elevated blood eosinophils (type 2-high), but limited options are available for patients with low blood eosinophils (type 2-low). Inhibiting IL-33 signaling may target pathogenic pathways in a wider spectrum of asthmatics. OBJECTIVES: This study evaluated astegolimab efficacy and safety in patients with severe asthma. METHODS: This double-blind, placebo-controlled, dose-ranging study (ZENYATTA [A Study to Assess the Efficacy and Safety of MSTT1041A in Participants With Uncontrolled Severe Asthma]) randomized 502 adults with severe asthma to subcutaneous placebo or 70-mg, 210-mg, or 490-mg doses of astegolimab every 4 weeks. The primary endpoint was the annualized asthma exacerbation rate (AER) at week 54. Enrollment caps ensured ∼30 patients who were eosinophil-high (≥300 cells/µL) and ∼95 patients who were eosinophil-low (<300 cells/µL) per arm. RESULTS: Overall, adjusted AER reductions relative to placebo were 43% (P = .005), 22% (P = .18), and 37% (P = .01) for 490-mg, 210-mg, and 70-mg doses of astegolimab, respectively. Adjusted AER reductions for patients who were eosinophil-low were comparable to reductions in the overall population: 54% (P = .002), 14% (P = .48), and 35% (P = .05) for 490-mg, 210-mg, and 70-mg doses of astegolimab. Adverse events were similar in astegolimab- and placebo-treated groups. CONCLUSIONS: Astegolimab reduced AER in a broad population of patients, including those who were eosinophil-low, with inadequately controlled, severe asthma. Astegolimab was safe and well tolerated.

Structure-based discovery of interleukin-33 inhibitors: a pharmacophore modelling, molecular docking, and molecular dynamics simulation approach.

Interleukin (IL)-33 is a new cytokine of the IL-1 family that is related to several inflammatory and autoimmune diseases. IL-33 binds to its ST2 receptor and leads to biological responses thereof. Currently, no drugs have been approved for the treatment of IL-33 related diseases. The aim of this study was to search for small molecules that inhibit the protein-protein interaction between IL-33 and ST2. A virtual screening was first performed to identify potential molecules that can bind IL-33. By analysing the interactions between key residues in the complex of IL-33/ST2, two pharmacophore hypotheses were then generated based on the 'mimicry' and 'pair-rule' principles. From a database of 62,074 compounds, 60 molecules satisfying the pharmacophore models were identified and docked to IL-33. Among 35 compounds successfully docked into the protein, 9 potential ligands in complex with IL-33 were selected for further analysis by molecular dynamics simulations. Based on the stability of the complexes and the interactions of each ligand with the key residues of IL-33, two compounds DB00158 and DB00642 were identified as the most potential inhibitors that can be further investigated as promising novel IL-33 inhibitory drugs.

Fibroblast-Derived IL33 Facilitates Breast Cancer Metastasis by Modifying the Immune Microenvironment and Driving Type 2 Immunity.

Lungs are one of the main sites of breast cancer metastasis. The metastatic microenvironment is essential to facilitate growth of disseminated tumor cells. Cancer-associated fibroblasts (CAF) are prominent players in the microenvironment of breast cancer. However, their role in the formation of a permissive metastatic niche is unresolved. Here we show that IL33 is upregulated in metastases-associated fibroblasts in mouse models of spontaneous breast cancer metastasis and in patients with breast cancer with lung metastasis. Upregulation of IL33 instigated type 2 inflammation in the metastatic microenvironment and mediated recruitment of eosinophils, neutrophils, and inflammatory monocytes to lung metastases. Importantly, targeting of IL33 in vivo resulted in inhibition of lung metastasis and significant attenuation of immune cell recruitment and type 2 immunity. These findings demonstrate a key function of IL33 in facilitating lung metastatic relapse by modulating the immune microenvironment. Our study shows a novel interaction axis between CAF and immune cells and reveals the central role of CAF in establishing a hospitable inflammatory niche in lung metastasis. SIGNIFICANCE: This study elucidates a novel role for fibroblast-derived IL33 in facilitating breast cancer lung metastasis by modifying the immune microenvironment at the metastatic niche toward type 2 inflammation.

Blocking of the IL-33/ST2 Signaling Axis by a Single-Chain Antibody Variable Fragment (scFv) Specific to IL-33 with a Defined Epitope.

Interleukin 33 (IL-33) is an IL-1 family cytokine that plays a central role in immune system by regulating and initiating inflammatory responses. The binding of IL-33 to the suppressor of tumorigenicity 2 (ST2) receptor induces mitogen-activated protein kinases (MAPK) and nuclear factor κB (NF-κB) pathways, thereby leading to inflammatory cytokines production in type 2 helper T cells and type 2 innate lymphoid cells. To develop an antibody specific to IL-33 with a defined epitope, we characterized a single-chain antibody variable fragments (scFvs) clone specific to IL-33, C2_2E12, which was selected from a human synthetic library of scFvs using phage display. Affinity (Kd) of C2_2E12 was determined to be 38 nM using enzyme-linked immunosorbent assay. C2_2E12 did not show cross-reactivity toward other interleukin cytokines, including closely related IL-1 family cytokines and unrelated proteins. Mutational scanning analysis revealed that the epitope of IL-33 consisted of residues 149-158 with key residues being L150 and K151 of IL-33. Structural modeling suggested that L150 and K151 residues are important for the interaction of IL-33 with C2_2E12, implicating that C2_2E12 could block the binding of ST2 to IL-33. Pull-down and in-cell assays supported that C2_2E12 can inhibit the IL-33/ST2 signaling axis. These results suggest that the scFv clone characterized here can function as a neutralizing antibody.

Single-Chain Soluble Receptor Fusion Proteins as Versatile Cytokine Inhibitors.

Cytokines are small secreted proteins that among many functions also play key roles in the orchestration of inflammation in host defense and disease. Over the past years, a large number of biologics have been developed to target cytokines in disease, amongst which soluble receptor fusion proteins have shown some promise in pre-clinical studies. We have previously shown proof-of-concept for the therapeutic targeting of interleukin (IL)-33 in airway inflammation using a newly developed biologic, termed IL-33trap, comprising the ectodomains of the cognate receptor ST2 and the co-receptor IL-1RAcP fused into a single-chain recombinant fusion protein. Here we extend the biophysical and biological characterization of IL-33trap variants, and show that IL-33trap is a stable protein with a monomeric profile both at physiological temperatures and during liquid storage at 4°C. Reducing the N-glycan heterogeneity and complexity of IL-33trap via GlycoDelete engineering neither affects its stability nor its inhibitory activity against IL-33. We also report that IL-33trap specifically targets biologically active IL-33 splice variants. Finally, we document the generation and antagonistic activity of a single-chain IL-4/13trap, which inhibits both IL-4 and IL-13 signaling. Collectively, these results illustrate that single-chain soluble receptor fusion proteins against IL-4, IL-13, and IL-33 are novel biologics that might not only be of interest for research purposes and further interrogation of the role of their target cytokines in physiology and disease, but may also complement monoclonal antibodies for the treatment of allergic and other inflammatory diseases.

Osthole attenuates ovalbumin­induced lung inflammation via the inhibition of IL­33/ST2 signaling in asthmatic mice.

Asthma is a common chronic inflammatory airway disease. Recent studies have reported that interleukin (IL)­33 is a potential link between the airway epithelium and Th2­type inflammatory responses, which are closely related to the progression of asthma. The IL­33 receptor, ST2, is highly expressed in group 2 innate lymphoid cells (ILC2s), Th2 cells, mast cells, eosinophils and natural killer (NK) cells. Cnidii Fructus is a Chinese herb with a long history of use in the treatment of asthma in China. Osthole is one of the major components of Cnidii Fructus. The present study examined the anti­asthmatic effects of osthole in mice and aimed to elucidate the underlying mechanisms involving the IL­33/ST2 pathway. BALB/c mice were sensitized and challenged with ovalbumin and then treated with an intraperitoneal injection of osthole (25 and 50 mg/kg). Subsequently, the airway hyper­responsiveness (AHR) and inflammation of the lungs were evaluated. The amounts of IL­4, IL­5, IL­13, interferon (IFN)­Î³ and IL­33 in the bronchoalveolar lavage fluid (BALF) were measured by Luminex assay and their mRNA levels in the lungs were measured by reverse transcription­quantitative PCR. The histopathology of the lungs was performed with H&E, PAS and Masson's staining. The expression of ST2 in the lungs was evaluated by immunohistochemistry. The data demonstrated that osthole markedly reduced AHR and decreased the number of eosinophils and lymphocytes in BALF. It was also observed that osthole significantly inhibited the release of Th2­type cytokines (IL­4, IL­5 and IL­13) and upregulated the IFN­Î³ level in BALF. Moreover, osthole significantly attenuated the IL­33 and ST2 expression in the lungs of asthmatic mice. On the whole, osthole attenuated ovalbumin­induced lung inflammation through the inhibition of IL­33/ST2 signaling in an asthmatic mouse model. These results suggest that osthole is a promising target for the development of an asthma medication.

The role of IL-17, IL-23 and IL-31, IL-33 in allergic skin diseases.

PURPOSE OF REVIEW: Allergic skin diseases such as urticaria, atopic dermatitis and allergic contact dermatitis are among the most common skin diseases with severe socioeconomic consequences. The pathogenesis of allergic skin diseases is complex. This review provides an overview of cytocines IL-17, IL-23, IL-31 and IL-33. RECENT FINDINGS: Current research results show a variety of immunological processes in the pathogenesis of the allergic skin diseases, including the role of cytokines. In addition to the Th1 and Th2 immune response, the immune response via Th17 is becoming increasingly important in allergic skin diseases but also the cytokines IL-23, IL-31 and IL-33 have been discussed in the literature recently. Different cytokines promote in a kind of orchestra the different symptoms seen in the different allergic skin diseases, including pruritus, dermatitis, mast cell mediator release and inflammation. SUMMARY: We are still in the early stages of understanding pathophysiology of allergic skin diseases and the role of various cytokines in the immune system. With the development of targeted antibodies against the proinflammatory cytokines, the variety of normal therapeutic options can be expected to evolve.

A helminth-derived suppressor of ST2 blocks allergic responses.

The IL-33-ST2 pathway is an important initiator of type 2 immune responses. We previously characterised the HpARI protein secreted by the model intestinal nematode Heligmosomoides polygyrus, which binds and blocks IL-33. Here, we identify H. polygyrus Binds Alarmin Receptor and Inhibits (HpBARI) and HpBARI_Hom2, both of which consist of complement control protein (CCP) domains, similarly to the immunomodulatory HpARI and Hp-TGM proteins. HpBARI binds murine ST2, inhibiting cell surface detection of ST2, preventing IL-33-ST2 interactions, and inhibiting IL-33 responses in vitro and in an in vivo mouse model of asthma. In H. polygyrus infection, ST2 detection is abrogated in the peritoneal cavity and lung, consistent with systemic effects of HpBARI. HpBARI_Hom2 also binds human ST2 with high affinity, and effectively blocks human PBMC responses to IL-33. Thus, we show that H. polygyrus blocks the IL-33 pathway via both HpARI which blocks the cytokine, and also HpBARI which blocks the receptor.

Paeoniflorin suppresses IL-33 production by macrophages.

Objective: Interleukin (IL)-33 has been attracting more and more attention as a new member of theIL-1 cytokine family in recent years. However, the underlying mechanisms referred to the regulation of endogenous IL-33 production are not fully illustrated. Paeoniflorin (PF) has been reported to possess multiple pharmacological activities, including anti-inflammation and anti-allergy. In this study, we aimed to investigate the effect of PF on IL-33 production by macrophages and explore the underlying mechanisms.Methods: In vivo, IL-33 production in mice after lipopolysaccharide (LPS) injection together with PF application was detected by enzyme-linked immunosorbent assay (ELISA). In vitro, MTT, Real-time PCR, ELISA, Calcium (Ca2+) imaging and Western blot were used to assess the cytotoxicity of PF, IL-33 expression at mRNA and protein levels, Ca2+ influx, protein kinase C (PKC) activity, nuclear factor-kappa B (NF-κB), and mitogen-activated protein kinase (MAPK) activation in LPS-stimulated RAW264.7 macrophages with PF administration.Results: Our results indicated that PF (5 and 25 mg/kg) significantly reduced the production of TNF-a, IL-1ß, and IL-33 in the peritoneal exudate of LPS-treated mice. In vitro assay, upregulation of PF concentration (≥ 20 µM) showed an increased cytotoxicity in RAW264.7 cells during the 24-h cell culture. PF (10 µM) inhibited IL-33 production, Ca2+ influx, PKC activity, NF-κB (p65) activation, and P38MAPK phosphorylation in LPS-treated macrophages. Notably, NF-κB inhibitor (BAY 11-7085), P38MAPK inhibitor (SB203580), and Ca2+ blocker (NiCl2) also curbed LPS-induced IL-33 production, respectively.Conclusions: PF suppresses IL-33 production by macrophages via inhibiting NF-κB and P38MAPK activation associated with the regulation of Ca2+ mobilization.

Isatis tinctoria L.-derived Petroleum Ether Extract Mediates Anti-inflammatory Effects via Inhibition of Interleukin-6, Interleukin-33 and Mast Cell Degranulation.

Isatis tinctoria L. (woad) has been used in medicine for centuries and has demonstrated anti-inflammatory effects. However, to date, no well-defined extracts with precise analysis of active substances have been developed. The aim of this study was to develop novel extracts of Isatis tinctoria L., and to characterize their active ingredients and anti-inflammatory properties. Various extracts of Isatis tinctoria L. were analysed for their active ingredients, and screened for anti-inflammatory effects using cyclooxygenase-2 activity assays. A petroleum ether extract was found to have the best effects, and was tested in a mouse model of acute allergic contact dermatitis. In the mouse model the petroleum ether extract resulted in significantly reduced ear swelling, oedema and inflammatory cell density. In mouse skin and human keratinocyte cultures, petroleum ether extract inhibited pro-inflammatory cytokine expression. Furthermore, human mast cell degranulation was significantly inhibited in LAD2 cell cultures. In conclusion, novel woad extracts were developed and shown to have anti-inflammatory properties in a contact hypersensitivity animal model and human keratinocytes. The production of such extracts and further characterization of their specific properties will enable determination of their potential dermatological effects in the treatment of inflamed and irritated skin.

ST2 Signaling in the Tumor Microenvironment.

Suppression of tumorigenicity 2 (ST2), also known as interleukin-1 receptor-like 1 (IL1RL1), is one of the natural receptors of IL-33. Three major isoforms, ST2L (transmembrane form), sST2 (soluble form), and ST2V, are generated by alternative splicing. Damage to stromal cells induces necrosis and release of IL-33, which binds to heterodimeric ST2L/IL-1RAcP complex on the membrane of a variety of immune cells. This IL-33/ST2L signal induces transcription of the downstream inflammatory and anti-inflammatory genes by activating diverse intracellular kinases and factors to mount an adequate immune response, even in tumor microenvironment. For example, activation of IL-33/ST2L signal may trigger Th2-dependent M2 macrophage polarization to facilitate tumor progression. Notably, sST2 is a soluble form of ST2 that lacks a transmembrane domain but preserves an extracellular domain similar to ST2L, which acts as a "decoy" receptor for IL-33. sST2 has been shown to involve in the inflammatory tumor microenvironment and the progression of colorectal cancer, non-small cell lung cancer, and gastric cancer. Therefore, targeting the IL-33/ST2 axis becomes a promising new immunotherapy for treatment of many cancers. This chapter reviews the recent findings on IL-33/ST2L signaling in tumor microenvironment, the trafficking mode of sST2, and the pharmacological strategies to target IL-33/ST2 axis for cancer treatment.

Blocking Interleukin-33 Alleviates the Joint Inflammation and Inhibits the Development of Collagen-Induced Arthritis in Mice.

Rheumatoid arthritis (RA) is considered a systemic chronic inflammatory joint disease characterized by chronic synovitis and cartilage and bone destruction. Interleukin-33 (IL-33) is a proinflammatory cytokine which is highly expressed in the synovium of RA patients and the joints of mice with collagen-induced arthritis (CIA) and exacerbates CIA in mice. However, the role of the IL-33-neutralizing antibody in the murine model of CIA remains unclear. In the present study, CIA mice were given intraperitoneally with polyclonal rabbit anti-murine IL-33 antibody (anti-IL-33) or normal rabbit IgG control after the first signs of arthritis. Administration of anti-IL-33 after the onset of disease significantly reduced the severity of CIA and joint damage compared with controls treated with normal rabbit IgG. Anti-IL-33 treatment also significantly decreased the serum levels of interferon-γ(IFN-γ),IL-6, IL-12, IL-33, and tumor necrosis factor-α (TNF-α). Moreover, anti-IL-33 treatment significantly downregulated the production of IFN-γ, IL-6, IL-12, IL-33, and TNF-α in ex vivo-stimulated spleen cells. Together, our results indicate that the IL-33-neutralizing antibody may provide a therapeutic strategy for RA by inhibiting the release of proinflammatory cytokines.

Combined blockade of IL-25, IL-33 and TSLP mediates amplified inhibition of airway inflammation and remodelling in a murine model of asthma.

BACKGROUND AND OBJECTIVE: Isolated blockade of IL-25, IL-33 and thymic stromal lymphopoietin (TSLP) has been shown to reduce airways inflammation and hyperresponsiveness in murine asthma model. The hypothesis that combined blockade of all three cytokines can accomplish this more effectively has never been addressed. METHODS: We studied a murine asthma model employing sensitization and challenge with ovalbumin (OVA) or saline control. To discern the effects of IL-33 blockade, we compared outcomes in strain identical, wild-type and IL-33 receptor (St2 -/- ) gene-deleted mice. We then examined, in the St2 -/- animals, the effects of additional, single or combined blockade of IL-25 and TSLP with blocking antibodies. Outcomes included airways reactivity, inflammatory cellular infiltration, epithelial cell metaplasia, deposition of fibrosis-related proteins, local Th2-type cytokine expression and total and specific serum IgE concentrations measured by ELISA and quantitative immunohistochemistry. RESULTS: St2 -/- gene deletion significantly reduced airways reactivity, inflammatory cellular infiltration, lung tissue expression of Th2 cytokines and fibrosis related proteins and serum total IgE in response to OVA sensitization and challenge. Additional administration of anti-IL-25 and anti-TSLP blocking antibodies to the St2 -/- mice further significantly reduced inflammation, Th2 cytokine expression, airways fibrosis and IgE production, while anti-TSLP alone reduced eosinophil infiltration and local IL-4 expression. The airways inflammatory cellular infiltrate and lung tissue expression of Th2 cytokine, but not fibrosis-related proteins were also reduced in the presence of isotype identical, control antibodies. CONCLUSION: Combined blockade of these three cytokines may better ameliorate airways pathological changes in this murine asthma model, with implications for human asthma.

Clarithromycin decreases rhinovirus replication and cytokine production in nasal epithelial cells from subjects with bronchial asthma: effects on IL-6, IL-8 and IL-33.

Rhinoviral infection is associated with an increased risk of asthma attacks. The macrolide clarithromycin decreases cytokine production in nasopharyngeal aspirates from patients with wheezing, but the effects of macrolides on cytokine production in nasal epithelial cells obtained from asthmatic subjects remain unclear. Here, human nasal epithelial cells were infected with type-14 rhinovirus (RV14), a major RV group. Titers and RNA of RV14 and cytokine concentrations, including IL-1ß and IL-6, were higher in the supernatants of the cells obtained from subjects with bronchial asthma (asthmatic group) than in those from the non-asthmatic group. Pretreatment with clarithromycin decreased RV14 titers, viral RNA and cytokine concentrations, and susceptibility to RV14 infection. Pretreatment with clarithromycin also decreased IL-33 production, which was detected after infection. Pretreatment with clarithromycin decreased the expression of intercellular adhesion molecule-1, the receptor for RV14, after infection, the number and fluorescence intensity of the acidic endosomes through which RV RNA enters the cytoplasm, and the activation of nuclear factor kappa-B proteins in nuclear extracts. These findings suggested that RV replication and cytokine production may be enhanced in nasal epithelial cells obtained from subjects with bronchial asthma and may be modulated by clarithromycin.

Resveratrol inhibits IL-33-mediated mast cell activation by targeting the MK2/3-PI3K/Akt axis.

Interleukin-33 (IL-33)/ST2-mediated mast cell activation plays important roles in the pathophysiology of allergic diseases. Hence, pharmacologically targeting the IL-33/ST2 pathway in mast cells could help to treat such diseases. We found that resveratrol inhibits IL-33/ST2-mediated mast cell activation. Resveratrol suppressed IL-33-induced IL-6, IL-13, and TNF-α production in mouse bone marrow-derived mast cells (BMMCs), mouse fetal skin-derived mast cells, and human basophils. Resveratrol also attenuated cytokine expression induced by intranasal administration of IL-33 in mouse lung. IL-33-mediated cytokine production in mast cells requires activation of the NF-κB and MAPK p38-MAPK-activated protein kinase-2/3 (MK2/3)-PI3K/Akt pathway, and resveratrol clearly inhibited IL-33-induced activation of the MK2/3-PI3K/Akt pathway, but not the NF-κB pathway, without affecting p38 in BMMCs. Importantly, resveratrol inhibited the kinase activity of MK2, and an MK2/3 inhibitor recapitulated the suppressive effects of resveratrol. Resveratrol and an MK2/3 inhibitor also inhibited IgE-dependent degranulation and cytokine production in BMMCs, concomitant with suppression of the MK2/3-PI3K/Akt pathway. These findings indicate that resveratrol inhibits both IL-33/ST2-mediated and IgE-dependent mast cell activation principally by targeting the MK2/3-PI3K/Akt axis downstream of p38. Thus, resveratrol may have potential for the prevention and treatment of broad ranges of allergic diseases.