Adenosine closes the K+ channel KCa3.1 in human lung mast cells and inhibits their migration via the adenosine A2A receptor

Human lung mast cells (HLMC) express the Ca2+-activated K+ channel KCa3.1, which opens following IgE-dependent activation. This hyperpolarises the cell membrane and potentiates both Ca2+ influx and degranulation. In addition, blockade of KCa3.1 profoundly inhibits HLMC migration to a variety of diverse chemotactic stimuli. KCa3.1 activation is attenuated by the β2adrenoceptor through a Gαs-coupled mechanism independent of cyclic AMP. Adenosine is an important mediator that both attenuates and enhances HLMC mediator release through the Gαs-coupled A2A and A2B adenosine receptors, respectively. We show that at concentrations that inhibit HLMC degranulation (10–5–10–3 M), adenosine closes KCa3.1 both dose-dependently and reversibly. KCa3.1 suppression by adenosine was reversed partially by the selective adenosine A2A receptor antagonist ZM241385 but not by the A2B receptor antagonist MRS1754, and the effects of adenosine were mimicked by the selective A2A receptor agonist CGS21680. Adenosine also opened a depolarising current carried by non-selective cations. As predicted from the role of KCa3.1 in HLMC migration, adenosine abolished HLMC chemotaxis to asthmatic airway smooth muscle-conditioned medium. In summary, the Gαs-coupled adenosine A2A receptor closes KCa3.1, providing a clearly defined mechanism by which adenosine inhibits HLMC migration and degranulation. A2A receptor agonists with channel-modulating function may be useful for the treatment of mast cell-mediated disease

IL-13 expression by blood T cells and not eosinophils is increased in asthma compared to non-asthmatic eosinophilic bronchitis

<p>Abstract</p> <p>Background</p> <p>In asthma interleukin (IL)-13 is increased in the airway compared with non-asthmatic eosinophilic bronchitis. Whether this differential expression is specific to the airway or is more generalised is uncertain.</p> <p>Methods</p> <p>We sought to examine IL-13 expression in peripheral blood T-cells and eosinophils in asthma and non-asthmatic eosinophilic bronchitis. Peripheral blood CD3+ cell and eosinophil intracellular IL-13 expression from subjects with asthma, non-asthmatic eosinophilic bronchitis and healthy controls was assessed. The effect of priming by asthmatic serum on the release of IL-13 by peripheral blood mononuclear cells from healthy subjects was examined and the serum from these subjects was analysed for a range of chemokines and cytokines.</p> <p>Results</p> <p>The median (IQR)% intracellular IL-13 expression by CD3+ cells was increased in asthma [5.3 (2.7–9.8)%; n = 12] compared to non-asthmatic eosinophilic bronchitis [1.1 (0.5–3)%; n = 7] and healthy controls [1.7 (0.2–3%); n = 9] (p = 0.02), but was not significantly different in eosinophils across the groups. IL-13 released from healthy peripheral blood mononuclear cells (n = 10) was increased by asthmatic serum [117 (47.8–198)pg/ml] compared to control [78.5 (42.6–128)pg/ml; p = 0.02), but was not affected by non-asthmatic serum.</p> <p>Conclusion</p> <p>Our findings support the view that IL-13 expression is increased in peripheral blood-derived T cells in asthma and that asthmatic serum up-regulates IL-13 release from healthy peripheral blood mononuclear cells.</p

Immunologic and pathologic characterization of a novel swine biomedical research model for eosinophilic esophagitis

Eosinophilic esophagitis (EoE) is a chronic allergy-mediated condition with an increasing incidence in both children and adults. Despite EoE's strong impact on human health and welfare, there is a large unmet need for treatments with only one recently FDA-approved medication for EoE. The goal of this study was to establish swine as a relevant large animal model for translational biomedical research in EoE with the potential to facilitate development of therapeutics. We recently showed that after intraperitoneal sensitization and oral challenge with the food allergen hen egg white protein (HEWP), swine develop esophageal eosinophilia—a hallmark of human EoE. Herein, we used a similar sensitization and challenge treatment and evaluated immunological and pathological markers associated with human EoE. Our data demonstrate that the incorporated sensitization and challenge treatment induces (i) a systemic T-helper 2 and IgE response, (ii) a local expression of eotaxin-1 and other allergy-related immune markers, (iii) esophageal eosinophilia (>15 eosinophils/0.24 mm2), and (iv) esophageal endoscopic findings including linear furrows and white exudates. Thereby, we demonstrate that our sensitization and oral challenge protocol not only induces the underlying immune markers but also the micro- and macro-pathological hallmarks of human EoE. This swine model for EoE represents a novel relevant large animal model that can drive translational biomedical research to develop urgently needed treatment strategies for EoE

The Influence of Manga on the Graphic Novel

This material has been published in The Cambridge History of the Graphic Novel edited by Jan Baetens, Hugo Frey, Stephen E. Tabachnick. This version is free to view and download for personal use only. Not for re-distribution, re-sale or use in derivative works. © Cambridge University PressProviding a range of cogent examples, this chapter describes the influences of the Manga genre of comics strip on the Graphic Novel genre, over the last 35 years, considering the functions of domestication, foreignisation and transmedia on readers, markets and forms

Membrane spanning 4A gene family expression and function in human mast cells

Mast cells are major effector cells of allergic and inflammatory disease. Thus understanding mechanisms of mast cell biology are of great interest to cell biology research. This study aimed to identify the expression and function of a newly identified gene family, the MS4A family, in human mast cells. This study identified 8 gene variants expressed in mast cells including 2 novel variants. All of the expressed genes were cloned and GFP and adenoviral constructs were generated. Quantitative RT-PCR demonstrated that all expressed gene variants were differentially regulated by mast cell stimulation with IgE, IgE/anti-lgE and stem cell factor (SCF) suggesting roles in mast cell biology. Transfections demonstrated that most proteins were trafficked to the cytoplasmic membrane, but some were trafficked to the nuclear membrane. This intracellular localisation of the MS4A family may be critical for their function. This was exemplified in this study by the function of a novel truncation (MS4A2trunc) of MS4A 2 (the beta chain of FceRI). MS4A2trunc was trafficked to the nuclear membrane, whereas MS4A 2 was trafficked to the cytoplasmic membrane. Overexpression of MS4A 2 using adenoviral transduction had no apparent effect on mast cell survival or proliferation. However, overexpression of MS4A2trunc profoundly inhibited mast cell proliferation and induced apoptosis via G2 phase cell cycle arrest. The removal of SCF from mast cell cultures upregulated the expression of MS4A2trunc. In addition, the slowly replicating primary human lung mast cells, and the mast cell line LAD-2 expressed MS4A2trunc. However, I was unable to demonstrate expression of MS4A2trunc in the rapidly replicating c-KIT gain-of-function mutated mast cell line HMC-1. Thus loss of expression of MS4A2trunc may be an important step in the development of mast cell neoplasia. This study has identified an entirely novel function for the MS4A 2 gene and has opened numerous avenues for future research on the MS4A family

Regulation of Trafficking and Signaling of the High Affinity IgE Receptor by Fc&epsilon;RI&beta; and the Potential Impact of Fc&epsilon;RI&beta; Splicing in Allergic Inflammation

Mast cells are tissue-resident immune cells that function in both innate and adaptive immunity through the release of both preformed granule-stored mediators, and newly generated proinflammatory mediators that contribute to the generation of both the early and late phases of the allergic inflammatory response. Although mast cells can be activated by a vast array of mediators to contribute to homeostasis and pathophysiology in diverse settings and contexts, in this review, we will focus on the canonical setting of IgE-mediated activation and allergic inflammation. IgE-dependent activation of mast cells occurs through the high affinity IgE receptor, Fc&epsilon;RI, which is a multimeric receptor complex that, once crosslinked by antigen, triggers a cascade of signaling to generate a robust response in mast cells. Here, we discuss Fc&epsilon;RI structure and function, and describe established and emerging roles of the &beta; subunit of Fc&epsilon;RI (Fc&epsilon;RI&beta;) in regulating mast cell function and Fc&epsilon;RI trafficking and signaling. We discuss current approaches to target IgE and Fc&epsilon;RI signaling and emerging approaches that could target Fc&epsilon;RI&beta; specifically. We examine how alternative splicing of Fc&epsilon;RI&beta; alters protein function and how manipulation of splicing could be employed as a therapeutic approach. Targeting Fc&epsilon;RI directly and/or IgE binding to Fc&epsilon;RI are promising approaches to therapeutics for allergic inflammation. The characteristic role of Fc&epsilon;RI&beta; in both trafficking and signaling of the Fc&epsilon;RI receptor complex, the specificity to IgE-mediated activation pathways, and the preferential expression in mast cells and basophils, makes Fc&epsilon;RI&beta; an excellent, but challenging, candidate for therapeutic strategies in allergy and asthma, if targeting can be realized

IgE alone promotes human lung mast cell survival through the autocrine production of IL-6

Background: Mast cells play a key role in asthma and recent evidence indicates that their ongoing activation in this disease is mediated, in part, via IgE in the absence of antigen. In this study we have examined whether IgE alone enhances human lung mast cell (HLMC) survival. Methods: Purified HLMC were cultured for 4 weeks and survival assays then performed over 10 days following cytokine withdrawal in the presence or absence of human myeloma IgE. Quantitative real time RT-PCR was carried out to examine IL-6 mRNA expression and IL-6 protein was measured in HLMC supernatants by ELISA. Results: IgE alone promoted the survival of HLMC in a dose-dependent manner following cytokine withdrawal. IgE-induced survival was eliminated with the addition of neutralising anti-IL-6 antibody but not by the addition of neutralising anti-stem cell factor. IgE sensitisation initiated profound upregulation of IL-6 mRNA in HLMC, and IL-6 concentrations were also raised in the culture supernatants of IgE-exposed cells. Conclusion: These data taken together suggest that IgE in the absence of antigen promotes HLMC survival through the autocrine production of IL-6. This provides a further mechanism through which IL-6 and IgE contribute to the pathogenesis of asthma, and through which anti-IgE therapy might achieve its therapeutic effect

IgE alone promotes human lung mast cell survival through the autocrine production of IL-6

Background: Mast cells play a key role in asthma and recent evidence indicates that their ongoing activation in this disease is mediated, in part, via IgE in the absence of antigen. In this study we have examined whether IgE alone enhances human lung mast cell (HLMC) survival. Methods: Purified HLMC were cultured for 4 weeks and survival assays then performed over 10 days following cytokine withdrawal in the presence or absence of human myeloma IgE. Quantitative real time RT-PCR was carried out to examine IL-6 mRNA expression and IL-6 protein was measured in HLMC supernatants by ELISA. Results: IgE alone promoted the survival of HLMC in a dose-dependent manner following cytokine withdrawal. IgE-induced survival was eliminated with the addition of neutralising anti-IL-6 antibody but not by the addition of neutralising anti-stem cell factor. IgE sensitisation initiated profound upregulation of IL-6 mRNA in HLMC, and IL-6 concentrations were also raised in the culture supernatants of IgE-exposed cells. Conclusion: These data taken together suggest that IgE in the absence of antigen promotes HLMC survival through the autocrine production of IL-6. This provides a further mechanism through which IL-6 and IgE contribute to the pathogenesis of asthma, and through which anti-IgE therapy might achieve its therapeutic effect

IgE alone promotes human lung mast cell survival through the autocrine production of IL-6-5

<p><b>Copyright information:</b></p><p>Taken from "IgE alone promotes human lung mast cell survival through the autocrine production of IL-6"</p><p>http://www.biomedcentral.com/1471-2172/9/2</p><p>BMC Immunology 2008;9():2-2.</p><p>Published online 23 Jan 2008</p><p>PMCID:PMC2257927.</p><p></p

IgE alone promotes human lung mast cell survival through the autocrine production of IL-6-4

<p><b>Copyright information:</b></p><p>Taken from "IgE alone promotes human lung mast cell survival through the autocrine production of IL-6"</p><p>http://www.biomedcentral.com/1471-2172/9/2</p><p>BMC Immunology 2008;9():2-2.</p><p>Published online 23 Jan 2008</p><p>PMCID:PMC2257927.</p><p></p>roducts. The product sizes corresponded to the expected size for both IL-6 and β-actin