Interleukin-3, -5, and granulocyte macrophage colony-stimulating factor induce adhesion and chemotaxis of human eosinophils via p38 mitogen-activated protein kinase and nuclear factor kappaB

Insight into IL-5 as a Potential Target for the Treatment of Allergic Diseases

Interleukin-5 functions as a B-cell differentiation factor, but more importantly, in the context of this review, it plays a variety of roles in eosinophil biology, including eosinophil differentiation and maturation in the bone marrow, and facilitates eosinophil migration to tissue sites, usually in the context of an allergic reaction. Given the availability of selective anti-IL-5 drugs such as mepolizumab and reslizumab, as well as the IL-5 receptor antagonist benralizumab, it is worth investigating whether they could be used in some cases of allergic disease. Asthma has a well-documented involvement of IL-5 in its pathophysiology and has clear benefits in the case of anti-IL-5 therapy; therefore, current knowledge is presented to provide a reference point for the study of less-described diseases such as atopic dermatitis, chronic rhinosinusitis, chronic spontaneous urticaria, and its association with both IL-5 and anti-IL-5 treatment options. We then review the current literature on these diseases, explain where appropriate potential reasons why anti-IL-5 treatments are ineffective, and then point out possible future directions for further research.

The Poststroke Peripheral Immune Response Is Differentially Regulated by Leukemia Inhibitory Factor in Aged Male and Female Rodents

Background

The goal of this study was to determine whether leukemia inhibitory factor (LIF) promotes anti-inflammatory activity after stroke in a sex-dependent manner.

Methods

Aged (18-month-old) Sprague-Dawley rats of both sexes underwent sham surgery or permanent middle cerebral artery occlusion (MCAO). Animals received three doses of intravenous LIF (125 μg/kg) or PBS at 6, 24, and 48 h before euthanization at 72 h. Spleen weights were measured immediately following euthanization. Western blot was used to measure protein levels of CCL8, CD11b, CXCL9, CXCL10, IL-12 p40, IL-3, and the LIF receptor (LIFR) in spleen tissue. ELISA was used to measure IL-1β, IL-6, TNFα, and IFNγ in spleen tissue. A Griess Assay was used to indirectly quantify NO levels via measurement of nitrite. Levels of cellular markers and inflammatory mediators were normalized to the baseline (sham) group from each sex. Statistical analysis was performed using two-way ANOVA and followed by Fisher's LSD post hoc test.

Results

Aged female rats showed a significantly lower spleen weight after MCAO, but showed a significant increase in spleen size after LIF treatment. This effect was observed in aged male rats, but not to as great of an extent. CD11b levels were significantly higher in the spleens of MCAO+PBS males compared to their female counterparts, but there was no significant difference in CD11b levels between MCAO+LIF males and females. LIF significantly increased CXCL9 after LIF treatment in aged male and female rats. LIFR and IL-3 were upregulated after LIF treatment in aged females. Splenic nitrate increased after MCAO but decreased after LIF treatment in aged females. Splenic nitrate levels did not increase after MCAO but did increase after LIF treatment in aged males. The following cytokines/chemokines were not altered by sex or treatment: TNFα, IL-6, IL-12 p40, CCL8, IFNγ, and CXCL10.

Conclusions

LIF treatment after permanent MCAO induces sex-dependent effects on the poststroke splenic response and the production of proinflammatory cytokines among aged rats.

Interleukin-5 in the Pathophysiology of Severe Asthma

Interleukin-5 (IL-5) exerts a central pathogenic role in differentiation, recruitment, survival, and degranulation of eosinophils. Indeed, during the last years, significant advances have been made in our understanding of the cellular and molecular mechanisms underlying the powerful actions of IL-5 finalized to the induction, maintenance, and amplification of eosinophilic inflammation. Therefore, IL-5 is a suitable target for add-on biological therapies based on either IL-5 inhibition (mepolizumab, reslizumab) or blockade of its receptor (benralizumab). These modern treatments can result in being definitely beneficial for patients with severe type 2 (T2)-high eosinophilic asthma, refractory to conventional anti-inflammatory drugs such as inhaled and even systemic corticosteroids.

Benralizumab in the treatment of severe asthma: design, development and potential place in therapy

Asthma is a widespread and heterogeneous inflammatory disease of the airways, which is characterized by several different phenotypes and endotypes. In particular, eosinophilic airway inflammation is a common pathologic trait of both allergic and nonallergic asthma. The key cytokine responsible for maturation, activation, recruitment, and survival of eosinophils is interleukin (IL)-5, which is mainly produced by T helper 2 (Th2) lymphocytes and group 2 innate lymphoid cells. Therefore, for uncontrolled patients with severe eosinophilic asthma, who are not fully responsive to corticosteroids, IL-5 represents a very important molecular target for add-on biological therapies. Among these new treatments, anti-IL-5 monoclonal antibodies such as mepolizumab and reslizumab have been developed and clinically evaluated. Furthermore, benralizumab is currently the only available biologic drug that specifically binds to the IL-5 receptor, thus preventing the interaction with its ligand and the consequent pro-inflammatory effects. The effectiveness of benralizumab in improving severe eosinophilic asthma has been well-documented by many randomized controlled trials.

Essential Mechanisms of Differential Activation of Eosinophils by IL-3 Compared to GM-CSF and IL-5

Compelling evidence has demonstrated that the eosinophils bring negative biological outcomes in several diseases, including eosinophilic asthma and hypereosinophilic syndromes. Eosinophils produce and store a broad range of toxic proteins and other mediators that enhance the inflammatory response and lead to tissue damage. For instance, in asthma, a close relationship has been demonstrated between increased lung eosinophilia, asthma exacerbation, and loss of lung function. The use of an anti-IL-5 therapy in severe eosinophilic asthmatic patients is efficient to reduce exacerbations. However, anti-IL-5-treated patients still display a relatively high amount of functional lung tissue eosinophils, indicating that supplemental therapies are required to damper the eosinophil functions. Our recent published works suggest that compared to IL-5, IL-3 can more strongly and differentially affect eosinophil functions. In this review, we summarize our and other investigations that have compared the effects of the three β-chain receptor cytokines (IL-5, GM-CSF and IL-3) on eosinophil biology. We focus on how IL-3 differentially activates eosinophils compared to IL-5 or GM-CSF.

Severe eosinophilic asthma: from the pathogenic role of interleukin-5 to the therapeutic action of mepolizumab

Mepolizumab is an anti-interleukin-5 (IL-5) humanized monoclonal antibody that has been recently approved as an add-on biological treatment for severe eosinophilic asthma, by both the US Food and Drug Administration (FDA) and the European Medicines Agency (EMA). Moreover, mepolizumab is also currently included within the step 5 of the Global Initiative for Asthma guidelines, as an add-on therapy for severe uncontrolled asthma. The relevant therapeutic benefits detectable in patients with refractory eosinophilic asthma receiving mepolizumab depend on the pivotal pathogenic role played by IL-5 in these subjects. Indeed, IL-5 is the key cytokine responsible for maturation, activation, proliferation, and survival of eosinophils. Therefore, IL-5 represents a strategic molecular target for anti-eosinophilic treatments. By selectively inhibiting the biological actions of IL-5, mepolizumab provides a valuable therapeutic option for patients with severe eosinophilic asthma, refractory to standard treatments including inhaled and even systemic corticosteroids. In particular, the very important advantages linked to the use of mepolizumab in these difficult-to-treat asthmatic individuals have been well documented by several different trials performed worldwide.

WITHDRAWN: Titanium dioxide nanoparticles induce human eosinophil adhesion onto endothelial EA.hy926 cells via activation of phosphoinositide 3-kinase/Akt cell signalling pathway

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Chromosome 17q21 Genes ORMDL3 and GSDMB in Asthma and Immune Diseases

Chromosome 17q21 contains a cluster of genes including ORMDL3 and GSDMB, which have been highly linked to asthma in genome-wide association studies. ORMDL3 is localized to the endoplasmic reticulum and regulates downstream pathways including sphingolipids, metalloproteases, remodeling genes, and chemokines. ORMDL3 inhibits serine palmitoyl-CoA transferase, the rate-limiting enzyme for sphingolipid biosynthesis. In addition, ORMDL3 activates the ATF6α branch of the unfolded protein response which regulates SERCA2b and IL-6, pathways of potential importance to asthma. The SNP-linking chromosome 17q21 to asthma is associated with increased ORMDL3 and GSDMB expression. Mice expressing either increased levels of human ORMDL3, or human GSDMB, have an asthma phenotype characterized by increased airway responsiveness and increased airway remodeling (increased smooth muscle and fibrosis) in the absence of airway inflammation. GSDMB regulates expression of 5-LO and TGF-β1 which are known pathways involved in the pathogenesis of asthma. GSDMB is one of four members of the GSDM family (GSDMA, GSDMB, GSDMC, and GSDMD). GSDMD (located on chromosome 8q24 and not linked to asthma) has emerged as a key mediator of pyroptosis. GSDMD is a key component of the NLPR3 inflammasome and is required for its activation. GSDMD undergoes proteolytic cleavage by caspase-1 to release its N-terminal fragment, which in turn mediates pyroptosis and IL-1β secretion. Chromosome 17q21 has not only been linked to asthma but also to type 1 diabetes, inflammatory bowel disease, and primary biliary cirrhosis suggesting that future insights into the biology of genes located in this region will increase our understanding of these diseases.

Role of biologics in severe eosinophilic asthma - focus on reslizumab

Within the context of the heterogeneous phenotypic stratification of asthmatic population, many patients are characterized by moderate-to-severe eosinophilic asthma, not adequately controlled by relatively high dosages of inhaled and even oral corticosteroids. Therefore, these subjects can obtain significant therapeutic benefits by additional biologic treatments targeting interleukin-5 (IL-5), given the key pathogenic role played by this cytokine in maturation, activation, proliferation, and survival of eosinophils. In particular, reslizumab is a humanized anti-IL-5 monoclonal antibody that has been found to be an effective and safe add-on therapy, capable of decreasing asthma exacerbations and significantly improving disease control and lung function in patients experiencing persistent allergic or nonallergic eosinophilic asthma, despite the regular use of moderate-to-high doses of inhaled corticosteroids. These important therapeutic effects of reslizumab, demonstrated by several controlled clinical trials, have led to the recent approval by US Food and Drug Administration of its use, together with other antiasthma medications, for the maintenance treatment of patients suffering from severe uncontrolled asthma.

Inflammatory cytokines in general and central obesity and modulating effects of physical activity

Context

Chronic systemic inflammation in obesity originates from local immune responses in visceral adipose tissue. However, assessment of a broad range of inflammation-mediating cytokines and their relationship to physical activity and adipometrics has scarcely been reported to date.

Objective

To characterize the profile of a broad range of pro- and anti-inflammatory cytokines and the impact of physical activity and energy expenditure in individuals with general obesity, central obesity, and non-obese subjects.

Design, Setting, and Participants

A cross-sectional study comprising 117 obese patients (body mass index (BMI) ≥ 30) and 83 non-obese community-based volunteers.

Main Outcomes Measures

Serum levels of interleukin (IL)-2, IL-4, IL-5, IL-10, IL-12, IL-13, granulocyte-macrophage colony-stimulating factor (GM-CSF), interferon (IFN)-γ and tumor necrosis factor (TNF)-α were measured. Physical activity and energy expenditure (MET) were assessed with actigraphy. Adipometrics comprised BMI, weight, abdominal-, waist- and hip-circumference, waist to hip ratio (WHR), and waist-to-height-ratio (WHtR).

Results

General obesity was associated with significantly elevated levels of IL-5, IL-10, IL-12, IL-13, IFN-γ and TNF-α, central obesity with significantly elevated IL-5, IL-10, IL-12, IL-13 and IFN-γ-levels. In participants with general obesity, levels of IL-4, IL-10 and IL-13 were significantly elevated in participants with low physical activity, even when controlled for BMI which was negatively associated with physical acitivity. Cytokines significantly correlated with adipometrics, particularly in obese participants.

Conclusions

Results confirm up-regulation of certain pro- and anti-inflammatory cytokines in obesity. In obese subjects, physical activity may lower levels and thus reduce pro-inflammatory effects of cytokines that may link obesity, insulin resistance and diabetes.

So-Cheong-Ryong-Tang, a herbal medicine, modulates inflammatory cell infiltration and prevents airway remodeling via regulation of interleukin-17 and GM-CSF in allergic asthma in mice

Background:

So-Cheong-Ryong-Tang (SCRT), herbal medicine, has been used for the control of respiratory disease in East Asian countries. However, its therapeutic mechanisms, especially an inhibitory effect on inflammatory cell infiltration and airway remodeling in allergic asthma are unclear.

Objective:

The present study investigated the mechanism of antiasthmatic effects of SCRT in allergic asthma in mice.

Materials and Methods:

We investigated the influence of SCRT on levels of interleukin-17 (IL-17), granulocyte/macrophage colony-stimulating factor (GM-CSF), IL-4, and interferon gamma (IFN-γ) in bronchoalveolar lavage fluid (BALF), ovalbumin (OVA)-specific IgE in serum, and histopathological changes in allergen-induced asthma.

Results:

So-Cheong-Ryong-Tang decreased levels of IL-17 and GM-CSF in BALF. IL-4, a Th2-driven cytokine, was also decreased by SCRT, but IFN-γ, a Th1-driven cytokine, was not changed. Levels of OVA-specific IgE in serum were also decreased by SCRT. With SCRT treatment, histopathological findings showed reduced tendency of inflammatory cell infiltration, and prevention from airway remodeling such as epithelial hyperplasia.

Conclusion:

In this study, we firstly demonstrated that regulation of IL-17 and GM-CSF production may be one of the mechanism contributed to a reduction of inflammatory cell infiltration and prevention from airway remodeling.

Cholesterol selectively regulates IL-5 induced mitogen activated protein kinase signaling in human eosinophils

Eosinophils function contributes to human allergic and autoimmune diseases, many of which currently lack curative treatment. Development of more effective treatments for eosinophil-related diseases requires expanded understanding of eosinophil signaling and biology. Cell signaling requires integration of extracellular signals with intracellular responses, and is organized in part by cholesterol rich membrane microdomains (CRMMs), commonly referred to as lipid rafts. Formation of these organizational membrane domains is in turn dependent upon the amount of available cholesterol, which can fluctuate widely with a variety of disease states. We tested the hypothesis that manipulating membrane cholesterol content in primary human peripheral blood eosinophils (PBEos) would selectively alter signaling pathways that depend upon membrane-anchored signaling proteins localized within CRMMs (e.g., mitogen activated protein kinase [MAPK] pathway), while not affecting pathways that signal through soluble proteins, like the Janus Kinase/Signal Transducer and Activator of Transcription [JAK/STAT] pathway. Cholesterol levels were increased or decreased utilizing cholesterol-chelating methyl-β-cyclodextrin (MβCD), which can either extract membrane cholesterol or add exogenous membrane cholesterol depending on whether MβCD is preloaded with cholesterol. Human PBEos were pretreated with MβCD (cholesterol removal) or MβCD+Cholesterol (MβCD+Chol; cholesterol delivery); subsequent IL-5-stimulated signaling and physiological endpoints were assessed. MβCD reduced membrane cholesterol in PBEos, and attenuated an IL-5-stimulated p38 and extracellular-regulated kinase 1/2 phosphorylation (p-p38, p-ERK1/2), and an IL-5-dependent increase in interleukin-1β (IL-1β) mRNA levels. In contrast, MβCD+Chol treatment elevated PBEos membrane cholesterol levels and basal p-p38, but did not alter IL-5-stimulated phosphorylation of ERK1/2, STAT5, or STAT3. Furthermore, MβCD+Chol pretreatment attenuated an IL-5-induced increase in cell survival at 48 hours, measured as total cellular metabolism. The reduction in cell survival following cholesterol addition despite unaltered STAT phosphorylation contradicts the current dogma in which JAK/STAT activation is sufficient to promote eosinophil survival, and suggests an additional, unidentified mechanism critically regulates IL-5-mediated human PBEos survival.

IL-5 induces suspended eosinophils to undergo unique global reorganization associated with priming

The experiments described herein define a unique program of polarization of suspended human eosinophils stimulated with IL-5 family cytokines. We found that eosinophil granules and the nucleus move in opposite directions to form, respectively, a granular compartment and the nucleopod, a specialized uropod occupied by the nucleus and covered with adhesion receptors, including P-selectin glycoprotein ligand-1, CD44, and activated αMβ2 integrin. Ligated IL-5 family receptors localize specifically at the tip of the nucleopod in proximity to downstream signaling partners Janus tyrosine kinase 2, signal transducer and activator of transcription-1 and -5, and extracellular signal-regulated kinase. Microscopy and effects of cytochalasin B and nocodazole indicate that remodeling of filamentous actin and reorientation of the microtubule network are required for eosinophil polarization and nucleopod formation. IL-5 induces persistent polarization and extracellular signal-regulated kinase redistribution that are associated with eosinophil priming, a robust response on subsequent stimulation with N-formyl-methionyl-leucyl-phenylalanine. Global reorganization of cytoskeleton, organelles, adhesion receptors, and signaling molecules likely facilitates vascular arrest, extravasation, migration, granule release, and survival of eosinophils entering inflamed tissues from the bloodstream.

The role of immune genes in the association between depression and inflammation: a review of recent clinical studies

The role for dysregulation of the immune system in the pathogenesis of depressive disorder is well established, and emerging research suggests the role of an underlying genetic vulnerability. The purpose of this review is to summarize the existing literature on the genetic variants involved in neurobiological pathways associated with both immune activation and depression. Using PubMed, Scopus, The Cochrane Library, Embase, Ovid of Medline, PsycINFO and ISI web of Knowledge, we selected 52 papers which are relevant for this literature review. Findings across the literature suggest that functional allelic variants of genes for interleukin-1beta (IL)-1β, tumor necrosis factor-alpha (TNF-α) and C-reactive protein (CRP), as well as genetic variations affecting T-cell function, may increase the risk for depression. Moreover, single nucleotide polymorphisms (SNPs) in the IL-1β, IL-6 and IL-11 genes, and in those regulating T-cell function may be associated with reduced responsiveness to antidepressant therapy. There is also some evidence indicative of a role of genetic variants of the enzymes, Cyclo-oxygenase2 (COX-2) and Phospholipase2 (PLA2), in the aetiology of depression. Finally, SNPs in genes related to the serotonin pathway may play a fundamental role in the shared genetic liability to both immune activation and depressive symptoms. Our review confirms that genetic variants influence the biological mechanisms by which the innate immune system contributes to the development of depression. However, future studies are necessary to identify the molecular mechanisms underlying these associations.

ORMDL3 promotes eosinophil trafficking and activation via regulation of integrins and CD48

ORM (yeast)-like protein isoform 3 (ORMDL3) has recently been identified as a candidate gene for susceptibility to asthma; however, the mechanisms by which it contributes to asthma pathogenesis are not well understood. Here we demonstrate a functional role for ORMDL3 in eosinophils in the context of allergic inflammation. Eosinophils recruited to the airways of allergen-challenged mice express ORMDL3. ORMDL3 expression in bone marrow eosinophils is localized in the endoplasmic reticulum and is induced by interleukin-3 and eotaxin-1. Overexpression of ORMDL3 in eosinophils causes increased rolling, distinct cytoskeletal rearrangement, extracellular signal-regulated kinase (1/2) phosphorylation and nuclear translocation of nuclear factor kappa B. Knockdown of ORMDL3 significantly inhibits activation-induced cell shape changes, adhesion and recruitment to sites of inflammation in vivo, combined with reduced expression of CD49d and CD18. In addition, ORMDL3 regulates interleukin-3-induced expression of CD48 and CD48-mediated eosinophil degranulation. These studies show that ORMDL3 regulates eosinophil trafficking, recruitment and degranulation, further elucidating a role for this molecule in allergic asthma and potentially other eosinophilic disorders.

Skepinone-L is a selective p38 mitogen-activated protein kinase inhibitor

Until now, a lack of inhibitors with high potency and selectivity in vivo has hampered investigation of the p38 mitogen-activated protein kinase (MAPK) signaling pathway. We describe the design of skepinone-L, which is, to our knowledge, the first ATP-competitive p38 MAPK inhibitor with excellent in vivo efficacy and selectivity. Therefore, skepinone-L is a valuable probe for chemical biology research, and it may foster the development of a unique class of kinase inhibitors.

Molecular and clinical rationale for therapeutic targeting of interleukin-5 and its receptor

Interleukin-5 is a Th2 homodimeric cytokine involved in the differentiation, maturation, migration, development, survival, trafficking and effector function of blood and local tissue eosinophils, in addition to basophils and mast cells. The IL-5 receptor (IL-5R) consists of an IL-5-specific α subunit that interacts in conformationally dynamic ways with the receptor's βc subunit, an aggregate of domains it shares with binding sites of IL-3 and granulocyte-macrophage colony-stimulating factor. IL-5 and IL-5R drive allergic and inflammatory immune responses characterizing numerous diseases, such as asthma, atopic dermatitis, chronic obstructive pulmonary disease, eosinophilic gastrointestinal diseases, hyper-eosinophilic syndrome, Churg-Strauss syndrome and eosinophilic nasal polyposis. Although corticosteroid therapy is the primary treatment for these diseases, a substantial number of patients exhibit incomplete responses and suffer side-effects. Two monoclonal antibodies have been designed to neutralize IL-5 (mepolizumab and reslizumab). Both antibodies have demonstrated the ability to reduce blood and tissue eosinophil counts. One additional monoclonal antibody, benralizumab (MEDI-563), has been developed to target IL-5R and attenuate eosinophilia through antibody-dependent cellular cytotoxicity. All three monoclonal antibodies are being clinically evaluated. Antisense oligonucleotide technology targeting the common βc IL-5R subunit is also being used therapeutically to inhibit IL-5-mediated effects (TPI ASM8). Small interfering RNA technology has also been used therapeutically to inhibit the expression of IL-5 in animal models. This review summarizes the structural interactions between IL-5 and IL-5R and the functional consequences of such interactions, and describes the pre-clinical and clinical evidence supporting IL-5R as a therapeutic target.

Altered expression of genes involved in inflammation and apoptosis in frontal cortex in major depression

The etiology of major depression (MDD), a common and complex disorder, remains obscure. Gene expression profiling was conducted on post-mortem brain tissue samples from Brodmann Area 10 (BA10) in the prefrontal cortex from psychotropic drug-free persons with a history of MDD and age, gender, and post-mortem interval-matched normal controls (n=14 pairs of subjects). Microarray analysis was conducted using the Affymetrix Exon 1.0 ST arrays. A set of differential expression changes was determined by dual-fold change-probability criteria (∣average log ratios∣>0.585 [equivalent to a 1.5-fold difference in either direction], P<0.01), whereas molecular pathways of interest were evaluated using Gene Set Enrichment Analysis software. The results strongly implicate increased apoptotic stress in the samples from the MDD group. Three anti-apoptotic factors, Y-box-binding protein 1, caspase-1 dominant-negative inhibitor pseudo-ICE, and the putative apoptosis inhibitor FKGS2, were over-expressed. Gene set analysis suggested up-regulation of a variety of pro- and anti-inflammatory cytokines, including interleukin 1α (IL-1α), IL-2, IL-3, IL-5, IL-8, IL-9, IL-10, IL-12A, IL-13, IL-15, IL-18, interferon gamma (IFNγ), and lymphotoxin α (TNF superfamily member 1). The genes showing reduced expression included metallothionein 1M (MT1M), a zinc-binding protein with a significant function in the modulation of oxidative stress. The results of this study indicate that post-mortem brain tissue samples from BA10, a region that is involved in reward-related behavior, show evidence of local inflammatory, apoptotic, and oxidative stress in MDD.

Chemoattractant-induced signaling via the Ras-ERK and PI3K-Akt networks, along with leukotriene C4 release, is dependent on the tyrosine kinase Lyn in IL-5- and IL-3-primed human blood eosinophils

Human blood eosinophils exhibit a hyperactive phenotype in response to chemotactic factors after cell "priming" with IL-5 family cytokines. Earlier work has identified ERK1/2 as molecular markers for IL-5 priming, and in this article, we show that IL-3, a member of the IL-5 family, also augments fMLP-stimulated ERK1/2 phosphorylation in primary eosinophils. Besides ERK1/2, we also observed an enhancement of chemotactic factor-induced Akt phosphorylation after IL-5 priming of human blood eosinophils. Administration of a peptide antagonist that targets the Src family member Lyn before cytokine (IL-5/IL-3) priming of blood eosinophils inhibited the synergistic increase of fMLP-induced activation of Ras, ERK1/2 and Akt, as well as the release of the proinflammatory factor leukotriene C(4). In this study, we also examined a human eosinophil-like cell line HL-60 clone-15 and observed that these cells exhibited significant surface expression of IL-3Rs and GM-CSFRs, as well as ERK1/2 phosphorylation in response to the addition of IL-5 family cytokines or the chemotactic factors fMLP, CCL5, and CCL11. Consistent with the surface profile of IL-5 family receptors, HL-60 clone-15 recapitulated the enhanced fMLP-induced ERK1/2 phosphorylation observed in primary blood eosinophils after priming with IL-3/GM-CSF, and small interfering RNA-mediated knockdown of Lyn expression completely abolished the synergistic effects of IL-3 priming on fMLP-induced ERK1/2 phosphorylation. Altogether, our data demonstrate a central role for Lyn in the mechanisms of IL-5 family priming and suggest that Lyn contributes to the upregulation of the Ras-ERK1/2 and PI3K-Akt cascades, as well as the increased leukotriene C(4) release observed in response to fMLP in "primed" eosinophils.

Proteasomal inhibition upregulates the endogenous MAPK deactivator MKP-1 in human airway smooth muscle: mechanism of action and effect on cytokine secretion

Asthma is a chronic inflammatory condition. Inhibition of the ubiquitin-proteasome system offers promise as a anti-inflammatory strategy, being responsible for the degradation of key proteins involved in crucial cellular functions, including gene expression in inflammation (e.g. inhibitory IkappaB-alpha and the endogenous MAPK deactivator - MKP-1). As MKP-1 inhibits MAPK-mediated pro-remodeling functions in human airway smooth muscle (ASM; a pivotal immunomodulatory cell in asthma) in this study we investigate the effect of the proteasome inhibitor MG-132 on MKP-1 and evaluate the anti-inflammatory effect of MG-132 on cytokine secretion from ASM cells. Examining the time-course of induction of MKP-1 mRNA and protein by MG-132 (10microM) we show that MKP-1 mRNA was first detected at 30min, increased to significant levels by 4h, resulting in a 12.6+/-1.5-fold increase in MKP-1 mRNA expression by 24h (P<0.05). MKP-1 protein levels corroborate the mRNA results. Investigating the effect of MG-132 on secretion of the cytokine IL-6 we show that while short-term pretreatment with MG-132 (30min) partially reduced TNFalpha-induced IL-6 via inhibition of IkappaB-alpha degradation and the NF-kappaB pathway, longer-term proteasome inhibition (up to 24h) robustly upregulated MKP-1 and was temporally correlated with repression of p38-mediated IL-6 secretion from ASM cells. Moreover, utilizing a cytokine array we show that MG-132 represses the secretion of multiple cytokines implicated in asthma. Taken together, our results demonstrate that MG-132 upregulates MKP-1 and represses cytokine secretion from ASM and highlight the potential of the proteasome as a therapeutic target in asthma.

Mature human eosinophils express functional Notch ligands mediating eosinophil autocrine regulation

Eosinophil chemotaxis and survival within tissues are key components in the development of tissue eosinophilia and subsequent effector responses. In this study, we demonstrate a novel mechanism of eosinophil autoregulation affecting migration and survival mediated through Notch signaling. We show for the first time that human blood eosinophils express Notch receptors and Notch ligands, expressions of which are influenced by the presence of eosinophil-activating granulocyte-macrophage colony-stimulating factor (GM-CSF). Evidence of Notch receptor activation and subsequent transcription of the Notch-responsive gene HES1 were observed in GM-CSF-stimulated eosinophils, confirming functionality of eosinophil-expressed Notch-signaling components. Moreover, by inhibiting Notch signaling with gamma-secretase inhibitors or Notch receptor-specific neutralizing antibodies, we demonstrate that autocrine Notch signaling enhances stimulus-mediated actin rearrangement and eosinophil chemokinesis, and impairs eosinophil viability. Taken together, these data suggest autocrine Notch signaling, enhanced in response to tissue- or inflammatory-derived signals, influences eosinophil activity and longevity, which may ultimately contribute to the development of tissue eosinophilia and exacerbation or remediation of eosinophil effector functions.

Rapid selective priming of FcalphaR on eosinophils by corticosteroids

Preactivation or priming of eosinophils by (proinflammatory) cytokines is important in the pathogenesis of allergic diseases. Several priming-dependent eosinophil responses, such as migration and adhesion, are reduced by treatment with corticosteroids. Many inhibitory effects of corticosteroids are mediated by the glucocorticoid receptor via genomic mechanisms, which are evident only after prolonged interaction (>30 min). However, also faster actions of corticosteroids have been identified, which occur in a rapid, nongenomic manner. In this study, fast effects of corticosteroids were investigated on the function of eosinophil opsonin receptors. Short term corticosteroid treatment of eosinophils for maximal 30 min with dexamethasone (Dex) did not influence eosinophil cell surface CD11b/CD18 expression, adhesion, and/or chemokinesis. In marked contrast, incubation with Dex resulted in a rapid increase in binding of IgA-coated beads to human eosinophils, showing that Dex can up-regulate the activation of FcalphaR (CD89). This priming response by Dex was dose dependent and optimal between 10(-8) and 10(-6) M and was mediated via the glucocorticoid receptor as its selective antagonist RU38486 (10(-6) M) blocked the priming effect. In contrast to FcalphaR, eosinophil FcgammaRII (CD32) was not affected by Dex. Further characterization of the Dex-induced inside-out regulation of FcalphaR revealed p38 MAPK as the central mediator. Dex dose dependently enhanced p38 MAPK phosphorylation and activation in situ as measured by phosphorylation of its downstream target mitogen-activated protein kinase-activated protein kinase 2. The dose responses of the Dex-induced activation of these kinases were similar as seen for the priming of FcalphaR. This work demonstrates that corticosteroids selectively activate the FcalphaR on eosinophils by activation of p38 MAPK.

CD69 expression on airway eosinophils and airway inflammation in a murine model of asthma

BACKGROUND

Asthma is a chronic airway disease with inflammation characterized by physiological changes (airway hyper-responsiveness, AHR) and pathological changes (inflammatory cells infiltration and mucus production). Eosinophils play a key role in the allergic inflammation. But the causative relationship between eosinophils and airway inflammation is hard to prove. One of the reasons is lack of activation marker of murine eosinophils. We investigated the expression of CD69 on murine eosinophils in vitro, the relationship between the expression of CD69 on eosinophils from peripheral blood and bronchoalveolar lavage fluid and on airway inflammation in asthmatic mice.

METHODS

Eosinophils from peripheral blood of IL-5 transgenic mice (NJ.1638) were purified. Mice were divided into five groups: wild type mice sensitized and challenged with saline (WS group), wild type mice sensitized and challenged with ovalbumin (WO group), IL-5(-/-) mice sensitized and challenged with saline and transferred with purified eosinophils (ISE group), IL-5(-/-) mice sensitized and challenged with OVA and transferred with purified eosinophils (IOE group), IL-5(-/-) mice sensitized and challenged with OVA and transferred with purified eosinophils, pretreated with anti CD4 monoclonal antibody (IOE+antiCD4mAb group). IL-5(-/-) mice were sensitized with OVA at day 0 and day 14, then challenged with OVA aerosol. On days 24, 25, 26 and 27 purified eosinophils were transferred intratracheally to IL-5(-/-) mice. On day 28, blood and BALF were collected and CD69 expression on eosinophils measured by flowcytometry.

RESULTS

Purified eosinophils did not express CD69. But eosinophils cultured with PMA + MA, IFN-gamma, IL-5 or GM-CSF expressed CD69 strongly. Eosinophils from blood of WO, WS group did not express CD69 at all. The numbers of eosinophils in BALF of WO group, IOE group, ISE group and IOE + antiCD4mAb group were significantly higher than in mice of WS group which did not have eosinophils at all. CD69 expression on eosinophils in BALF of IOE and WO groups was strong. Eosinophils in BALF of ISE and IOE + antiCDmAb groups did not express CD69. The mucus production result was similar to CD69 expression. There were eosinophils infiltration in lung slides of all groups except WS group.

CONCLUSION

Activation in airway of eosinophils could directly lead to airway inflammation.