IgE-mediated Anaphylactic Reactions Research Articles

Identification of an immunodominant IgE epitope of Der f 40, a novel allergen of Dermatophagoides farinae

BackgroundHouse dust mites (HDMs), including Dermatophagoides pteronyssinus (Der p) and Dermatophagoides farinae (Der f) species, represent a major source of inhalant allergens that induce IgE-mediated anaphylactic reactions. HDM allergen identification is important to the diagnosis and treatment of allergic diseases. Here, we report the identification of a novel HDM allergen, which we suggest naming Der f 40, and its immunodominant IgE epitopes. MethodsThe recombinant protein Der f 40 was expressed using a pET prokaryotic expression system and purified with Ni-NTA resins. IgE binding activity was evaluated by IgE-western blot, dot-blot, and ELISA. Mast cell activation testing was performed to assess the cellular effects of IgE binding in mouse bone marrow derived mast cells (BMMCs) expressing human FcεRI. IgE binding assays were performed with truncated and hybrid Der f 40 protein molecules to find immunodominant IgE epitopes. ResultsA 106-amino acid (aa) recombinant Der f Group 40 protein (rDer f 40) was obtained (GenBank accession No. XP_046915420.1) as thiredoxin-like protein. Der f 40 was shown to bind IgE from HDM allergic serum in vitro (9.68%; 12/124 in IgE-ELISA), and shown to promote the release of β-hexosaminidase from BMMCs dose-dependently when administered with HDM allergic sera. The Der f Group 40 protein was named Der f 40 and listed in the World Health Organization and International Union of Immunological Societies (WHO/IUIS) Allergen Nomenclature Sub-committee. IgE binding assays with Der f 40-based truncated and hybrid proteins indicated that IgE binding epitopes are likely located in the C-terminal region and dependent on conformational structure. The 76–106-aa region of C-terminus was identified as an immunodominant IgE epitope of Der f 40. ConclusionA novel HDM allergen with robust IgE binding activity was identified and named Der f 40. An immunodominant IgE epitope of Der f 40 with conformational dependency was identified in the C-terminus (aa 76–106). These findings provide new information that may be useful in the development of diagnostic and therapeutic agents for HDM allergy.

Adults with possible food protein-induced enterocolitis syndrome with crustacean ingestion

BackgroundFood protein-induced enterocolitis (FPIES), an entity previously thought to only affect children, has been increasingly described in adults. In this study, we report a Canadian cohort of 19 adolescents and adults with recurrent non-immunoglobulin E (IgE)-mediated gastrointestinal symptoms after crustacean ingestion, consistent with FPIES.MethodsWe conducted a retrospective chart review of patients in an outpatient allergy clinic from January 2005 to May 2020. Electronic records were searched using keywords for crustaceans and for symptoms consistent with FPIES. We included patients with gastrointestinal symptoms specifically to crustaceans on more than one occasion, who were 14 years or older at the time of index reaction. Exclusion criteria included symptoms suggestive of an IgE-mediated anaphylactic reaction or a likely alternative diagnosis. We identified 19 patients for our cohort who met the criteria.ResultsOur cohort was 68.4% female (13) and 32.6% (6) male. The average age at first reaction to crustaceans was 34 years old with a range of 14–68 years (median = 28 years; IQR = 32 years). Time from ingestion to beginning of symptoms ranged from 3 min to 6.5 h, with an average of 2.8 h (median = 2 h; IQR = 3.25 h). Duration of reaction ranged from less than a minute to over 48 h, with a mean of 9.4 h (median = 4 h; IQR = 7.75 h). Patients had 4.8 reactions on average; however, number of reactions ranged from 2 to 12.5 (median = 3, IQR = 3). All patients identified a “trigger” food in the crustacean group, and 12 subjects identified additional reactions to other seafood.ConclusionsThis case series will better characterize and advance our understanding of this disease entity in adults. There are key differences in the presentation of FPIES in adults compared to children, namely female predominance, difference in solid food trigger, and unpredictable time course. Future studies are needed to examine the pathophysiology and natural history of adult FPIES. Specific guidelines should be developed for the diagnosis and management in adults.Trial registration: retrospectively registered.

A rare case of anaphylaxis to Indian jujube (Ziziphus Mauritiana Lam)

BackgroundIndian jujube (Ziziphus Mauritiana Lam) is a sweet fruit from a tree native to tropical and subtropical regions of Asia and India. A few case reports have implicated Indian jujube to cause latex-fruit syndrome. We present the first case of an anaphylactic reaction to this fruit in a patient with no latex allergy.Case presentationA 55-year-old male was referred to the Outpatient Allergy Clinic at Queen’s University for evaluation of anaphylaxis caused by ingestion of Indian jujube. He presented to the Emergency Department (ED) with scalp pruritus, dyspnea and generalized urticaria, which occurred two hours after he had consumed a homemade candied fruit cocktail consisting of Indian jujube, water, Thai and Indian sweetener. In the ED, he was treated with epinephrine, intravenous diphenhydramine and steroids. He did not have any previous history of environmental or food allergies but had consumed this fruit frequently since childhood. In clinic, he underwent skin-prick testing with a saline slurry of candied jujube, which resulted in a positive wheal and flare response with appropriate controls. On subsequent visit, skin-prick tests were performed with saline slurries of the Thai and Indian sweetener used to make the cocktail. Both tests were negative when applied to a healthy volunteer. Skin-prick testing to latex allergen and latex specific IgE were both negative. He was diagnosed with an IgE-mediated anaphylactic reaction to the Indian jujube fruit. He was advised to avoid consumption of Indian jujubes and carry an epinephrine autoinjector.ConclusionsAnaphylaxis secondary to Indian jujube ingestion is an extremely rare phenomenon in patients without a latex allergy. A possible allergy to Indian jujube should be taken into consideration when working up anaphylaxis, especially in patient of Asian and Indian descent who have ceased regular consumption of the fruit.

IgE-mediated anaphylactic reaction against free synthetic folic acid and methyl folate

IgE-mediated anaphylactic reaction against free synthetic folic acid and methyl folate

Dehydroandrographolide inhibits IgE-mediated anaphylactic reactions via calcium signaling pathway

The classical mast cells degranulation pathway is mediated by FcεRI aggregation and varies in strength among subjects. Dehydroandrographolide (DA) is one of principal components of Andrographis paniculata (Burm.f.) Nees (family: Acanthaceae) and considered the main contributors of its therapeutic properties, such as anti-tumor. In this study, inhibition of IgE-mediated anaphylactic reactions and anti-inflammatory potential of DA were investigated. The anti-anaphylactic activity of DA was investigated using skin swelling and extravasation assays in vivo and mast cell degranulation assay in vitro. The release of cytokines was measured using ELISA kits. Human Phospho-Kinase Array kit and western blotting were used to explore the related molecular signaling pathways. DA inhibited IgE-mediated mast cell activation, including degranulation and release of cytokines in vitro. Moreover, DA reduced the degree of swelling and Evans blue exudation of mice paw in a dose-dependent manner by inhibiting mast cell degranulation. DA obviously reduced the concentrations of histamine, TNF-α, MCP-1, IL-8, IL-13, and IL-4 in mice serum and inhibited IgE-mediated anaphylactic reactions as a potential P-PLCγ inhibitor. Our study reveals that DA can inhibit allergic responses in vivo and in vitro, and it may be regarded as a novel P-PLCγ inhibitor for preventing mast cell-immediate and delayed allergic diseases.

Mas-Related G Protein-Coupled Receptor-X2 (MRGPRX2) in Drug Hypersensitivity Reactions.

The human ortholog MRGPRX2 and the mice ortholog, Mrgprb2 are activated by basic secretagogues and neurokinins. A number of commonly used small-molecule drugs (e.g., neuromuscular blocking agents, fluoroquinolones, vancomycin) have been recently shown to activate these receptors under in vitro experimental conditions, what results in mast cell degranulation. The above drugs are also known to cause IgE-mediated anaphylactic reactions in allergic patients. The new findings on mechanisms of drug-induced mast cell degranulation may modify the current management of drug hypersensitivity reactions. Clinical interpretation of mild drug-provoked hypersensitivity reactions, interpretation of skin test with a drug of interest or further recommendations for patients suspected of drug allergy are likely to be reconsidered. In the paper we discussed future directions in research on identification and differentiation of MRGPRX2-mediated and IgE-dependent mast cell degranulation in patients presenting clinical features of drug-induced hypersensitivity reactions.

Identification, expression and characterization of the recombinant Sol g 4.1 protein from the venom of the tropical fire ant Solenopsis geminata

BackgroundFire ant venom is a complex mixture consisting of basic piperidine alkaloids, various biologically active peptides and protein components, including a variety of major allergenic proteins. Tropical fire ant Solenopsis geminata is an important stinging ant species that causes anaphylaxis and serious medical problems. Although the biological activities of allergenic venom proteins that are unique to ant venom, particularly Solenopsis 2 and 4, are still unknown, these proteins are believed to play important roles in mediating the effects of the piperidine derivatives in the venom.MethodsIn the present study, the cDNA cloning, sequencing and three-dimensional structure of Sol g 4.1 venom protein are described. The recombinant Sol g 4.1 protein (rSol g 4.1) was produced in E. coli, and its possible function as a hydrophobic binding protein was characterized by paralyzing crickets using the 50% piperidine dose (PD50). Moreover, an antiserum was produced in mice to determine the allergenic properties of Sol g 4.1, and the antiserum was capable of binding to Sol g 4.1, as determined by Western blotting.ResultsThe molecular weight of Sol g 4.1 protein is 16 kDa, as determined by SDS-PAGE. The complete cDNA is 414 bp in length and contains a leader sequence of 19 amino acids. The protein consists of six cysteines that presumably form three disulfide bonds, based on a predicted three-dimensional model, creating the interior hydrophobic pocket and stabilizing the structure. The rSol g 4.1 protein was expressed in inclusion bodies, as determined by SDS-PAGE. Dialysis techniques were used to refold the recombinant protein into the native form. Its secondary structure, which primarily consists of α-helices, was confirmed by circular dichroism analysis, and the three-dimensional model was also verified. The results of allergenic analysis performed on mice showed that the obtained protein was predicted to be allergenically active. Moreover, we report on the possible role of the Sol g 4.1 venom protein, which significantly reduced the PD50 from 0.027 to 0.013% in paralyzed crickets via synergistic effects after interactions with piperidine alkaloids.ConclusionsThe primary structure of Sol g 4.1 showed high similarity to that of venom proteins in the Solenopsis 2 and 4 family. Those proteins are life-threatening and produce IgE-mediated anaphylactic reactions in allergic individuals. The possible function of this protein is the binding of the interior hydrophobic pockets with piperidine alkaloids, as determined by the analysis of the structural model and PD50 test.

The vascular endothelial specific IL-4 receptor alpha–ABL1 kinase signaling axis regulates the severity of IgE-mediated anaphylactic reactions

Severe IgE-mediated, food-induced anaphylactic reactions are characterized by pulmonary venous vasodilatation and fluid extravasation, which are thought to lead to the life-threatening anaphylactic phenotype. The underlying immunologic and cellular processes involved in driving fluid extravasation and the severe anaphylactic phenotype are not fully elucidated. We sought to define the interaction and requirement of IL-4 and vascular endothelial (VE) IL-4 receptor α chain (IL-4Rα) signaling in histamine-abelson murine leukemia viral oncogene homology 1 (ABL1)-mediated VE dysfunction and fluid extravasation in the severity of IgE-mediated anaphylactic reactions in mice. Mice deficient in VE IL-4Rα and models of passive and active oral antigen- and IgE-induced anaphylaxis were used to define the requirements of the VE IL-4Rα and ABL1 pathway in severe anaphylactic reactions. The human VE cell line (EA.hy926cells) and pharmacologic (imatinib) and genetic (short hairpin RNA knockdown of IL4RA and ABL1) approaches were used to define the requirement of this pathway in VE barrier dysfunction. IL-4 exacerbation of histamine-induced hypovolemic shock in mice was dependent on VE expression of IL-4Rα. IL-4- and histamine-induced ABL1 activation in human VE cells and VE barrier dysfunction was ABL1-dependent. Development of severe IgE-mediated hypovolemia and shock required VE-restricted ABL1 expression. Treatment of mice with a history of food-induced anaphylaxis with the ABL kinase inhibitor imatinib protected the mice from severe IgE-mediated anaphylaxis. IL-4 amplifies IgE- and histamine-induced VE dysfunction, fluid extravasation, and the severity of anaphylaxis through a VE IL-4Rα/ABL1-dependent mechanism. These studies implicate an important contribution by the VE compartment in the severity of anaphylaxis and identify a new pathway for therapeutic intervention of IgE-mediated reactions.

Vascular Endothelium–Specific IL-4Ra Signaling Axis Regulates Severity of IgE-Mediated Anaphylactic Reactions

Vascular Endothelium–Specific IL-4Ra Signaling Axis Regulates Severity of IgE-Mediated Anaphylactic Reactions

Cloning, structural modelling and characterization of VesT2s, a wasp venom hyaluronidase (HAase) from Vespa tropica.

BackgroundWasp venom is a complex mixture containing proteins, enzymes and small molecules, including some of the most dangerous allergens. The greater banded wasp (Vespa tropica) is well-known for its lethal venom, whose one of the major components is a hyaluronidase (HAase). It is believed that the high protein proportion and activity of this enzyme is responsible for the venom potency.MethodsIn the present study, cDNA cloning, sequencing and 3D-structure of Vespa tropica venom HAase were described. Anti-native HAase antibody was used for neutralization assay.ResultsTwo isoforms, VesT2a and VesT2b, were classified as members of the glycosidase hydrolase 56 family with high similarity (42–97 %) to the allergen venom HAase. VesT2a gene contained 1486 nucleotide residues encoding 357 amino acids whereas the VesT2b isoform consisted of 1411 residues encoding 356 amino acids. The mature VesT2a and VesT2b are similar in mass and pI after prediction. They are 39119.73 Da/pI 8.91 and 39571.5 Da/pI 9.38, respectively. Two catalytic residues in VesT2a, Asp107 and Glu109 were substituted in VesT2b by Asn, thus impeding enzymatic activity. The 3D-structure of the VesT2s isoform consisted of a central core (α/β)7 barrel and two disulfide bridges. The five putative glycosylation sites (Asn79, Asn99, Asn127, Asn187 and Asn325) of VesT2a and the three glycosylation sites (Asn1, Asn66 and Asn81) in VesT2b were predicted. An allergenic property significantly depends on the number of putative N-glycosylation sites. The anti-native HAase serum specifically recognized to venom HAase was able to neutralize toxicity of V. tropica venom. The ratio of venom antiserum was 1:12.ConclusionsThe wasp venom allergy is known to cause life-threatening and fatal IgE-mediated anaphylactic reactions in allergic individuals. Structural analysis was a helpful tool for prediction of allergenic properties including their cross reactivity among the vespid HAase.

Hypersensitivity to intravenous iron: classification, terminology, mechanisms and management.

Intravenous (IV) iron therapy is widely used in iron deficiency anaemias when oral iron is not tolerated or ineffective. Administration of IV-iron is considered a safe procedure, but severe hypersensitivity reactions (HSRs) can occur at a very low frequency. Recently, new guidelines have been published by the European Medicines Agency with the intention of making IV-iron therapy safer; however, the current protocols are still non-specific, non-evidence-based empirical measures which neglect the fact that the majority of IV-iron reactions are not IgE-mediated anaphylactic reactions. The field would benefit from new specific and effective methods for the prevention and treatment of these HSRs, and the main goal of this review was to highlight a possible new approach based on the assumption that IV-iron reactions represent complement activation-related pseudo-allergy (CARPA), at least in part. The review compares the features of IV-iron reactions to those of immune and non-immune HSRs caused by a variety of other infused drugs and thus make indirect inferences on IV-iron reactions. The process of comparison highlights many unresolved issues in allergy research, such as the unsettled terminology, multiple redundant classifications and a lack of validated animal models and lege artis clinical studies. Facts and arguments are listed in support of the involvement of CARPA in IV-iron reactions, and the review addresses the mechanism of low reactogenic administration protocols (LRPs) based on slow infusion. It is suggested that consideration of CARPA and the use of LRPs might lead to useful new additions to the management of high-risk IV-iron patients.

Loss of IL-4Rα-mediated PI3K signaling accelerates the progression of IgE/mast cell-mediated reactions.

Clinical and experimental evidence indicate that polymorphisms within the interleukin 4 (IL-4) receptor (IL-4R) chain are sufficient for altered strength of IL-4/IL-13 signaling, leading to an exaggerated allergic inflammatory response and increase susceptibility to allergic phenotypes. In the present study, we show that ablation of IL-4Rα-induced phosphatidylinositol 3-kinase (PI3K) activating signal by germline point mutation within the IL-4Rα motif (Y500F) did not alter susceptibility to IgE-mediated, food-induced experimental anaphylaxis. Moreover, diarrhea occurrence, antigen-specific IgE and intestinal mastocytosis were comparable between WT and IL-4Rα(Y500F) mice. However, mice unable to stimulate IL-4Rα-mediated PI3K signaling had accelerated disease progression. Notably, the accelerated anaphylactic response was associated with more rapid histamine-induced hypovolemia. Mechanistic in vitro and in vivo analyses revealed that endothelial IL-4Rα PI3K signaling negatively regulates the histamine-induced endothelial leak response. These results define an unanticipated role for IL-4Rα-mediated PI3K signaling in negative regulation of IgE-mediated anaphylactic reactions.

Effects of venom immunotherapy on serum level of CCL5/RANTES in patients with Hymenoptera venom allergy

Hymenoptera venoms are known to cause life-threatening IgE-mediated anaphylactic reactions in allergic individuals. Venom immunotherapy is a recommended treatment of insect allergy with still the mechanism not being completely understood. We decided to assess the serum CCL5/RANTES level in patients who experienced severe anaphylactic reaction to Hymenoptera venom and to find out changes in the course of immunotherapy. Twenty patients (9 men, 11 women, mean age: 31.91 ± 7.63 years) with history of anaphylactic reaction after insect sting were included into the study. Diagnosis was made according to sIgE and skin tests. All of them were enrolled into rush venom immunotherapy with bee or wasp venom extracts (Pharmalgen, ALK-Abello, Horsholm, Denmark). Serum levels of CCL5/RANTES were measured using a commercially available ELISA kit (R&D Systems, Minneapolis, MN). CCL5/RANTES serum concentration are higher in insect venom allergic patients than in healthy controls (887.5 ± 322.77 versus 387.27 ± 85.11 pg/ml). Serum concentration of CCL5/RANTES in insect venom allergic patient was significantly reduced in the course of allergen immunotherapy already after 6 days of vaccination (887.5 ± 322.77 versus 567.32 ± 92.16 pg/ml). CCL5/RANTES serum doesn’t correlate with specific IgE. Chemokine CCL5/RANTES participates in allergic inflammation induced by Hymenoptera venom allergens. Specific immunotherapy reduces chemokine CCL5/RANTES serum level already after initial days of venom immunotherapy.

Investigation of drugs responsible for perioperative anaphylactic reactions using cellular allergen stimulation test

Background Anaphylactic reactions during anesthesia and operation are common and life threatening. Follow-up investigation is necessary for avoiding potential re-exposure of the patients to the offending drugs. The purpose of this study was to assess cellular allergen stimulation test (CAST) as a diagnostic instrument in immunoglobulin E (IgE)- and non-IgE-mediated anaphylactic reactions. Methods This study included 25 patients who developed perioperative anaphylactic reactions and 10 subjects that tolerated anesthetics and other drugs during perioperative period from September 2009 to October 2013 in Peking Union Medical College Hospital. We performed skin tests and flow cytometric analysis of basophil activation-based CAST in all subjects. Results Of the 25 patients, 17 had IgE-mediated anaphylactic reactions (causative agent identified by skin tests) and 8 had non-IgE-mediated anaphylactic reactions (negative skin tests). CAST showed a sensitivity of 42.9%, specificity of 90%, and negative predictive value of 80.6% for neuromuscular blocking agents. Conclusions CAST may be useful for the diagnosis of anaphylactic reactions during perioperative period. Our findings call for further investigation to increase the sensitivity of the test.

Disruption of the suprachiasmatic nucleus blunts a time of day-dependent variation in systemic anaphylactic reaction in mice.

Anaphylaxis is a severe systemic allergic reaction which is rapid in onset and potentially fatal, caused by excessive release of mediators including histamine and cytokines/chemokines from mast cells and basophils upon allergen/IgE stimulation. Increased prevalence of anaphylaxis in industrialized countries requires urgent needs for better understanding of anaphylaxis. However, the pathophysiology of the disease is not fully understood. Here we report that the circadian clock may be an important regulator of anaphylaxis. In mammals, the central clock located in the suprachiasmatic nucleus (SCN) of the hypothalamus synchronizes and entrains peripheral circadian clock present in virtually all cell types via neural and endocrine pathways, thereby driving the daily rhythms in behavior and physiology. We found that mechanical disruption of the SCN resulted in the absence of a time of day-dependent variation in passive systemic anaphylactic (PSA) reaction in mice, associated with loss of daily variations in serum histamine, MCP-1 (CCL2), and IL-6 levels. These results suggest that the central SCN clock controls the time of day-dependent variation in IgE-mediated systemic anaphylactic reaction, which may provide a novel insight into the pathophysiology of anaphylaxis.

Rocuronium anaphylaxis in a 3-year-old girl with no previous exposure to neuromuscular blocking agents

During the perioperative period, anaphylactic reactions rarely occur. Neuromuscular blocking agents (NMBAs) are responsible for 60-70% of perioperative anaphylactic reactions. This case, we report a case of rocuronium-induced anaphylaxis in a 3-year-old girl with no previous exposure to NMBAs. This case cautions and informs practitioners that an IgE-mediated anaphylactic reaction with rocuronium is possible even in young children with no previous exposure to NMBAs.

Introduction to Special Issue on Food Allergy

This special issue of Seminars in Immunopathology reviews recent progress in our understanding of food allergy. Foodsensitive enteropathies can be defined as reproducible clinical response(s) to a given food (or foods) that are governed by an aberrant (typically Th2-mediated) immune response. Pathological responses to innocuous food antigens can be both IgEand non-IgE-mediated. This volume will focus primarily on the IgE-mediated anaphylactic reactions to food that are a growing public health concern in westernized countries [1]. Food allergies are increasingly common, especially in children. In the USA three million children (four out of every 100) were reported to have an allergic response to food in 2007, an increase of almost 20 % in just 10 years [2]. Similar trends have been reported in the UK [3] and in Australia [4]. Several reports indicate that, in the USA, allergic responses to food are the most frequent cause of anaphylactic reactions evaluated in the emergency room [5, 6]. For reasons that are not yet clear, 90 % of hypersensitivity reactions are attributable to only eight major types of food: milk, eggs, shellfish (particularly crustaceans), peanuts, soybeans, tree nuts, and wheat. Allergic responses to milk, soybeans, eggs, and wheat are typically transient and restricted to childhood; while peanuts, tree nuts, and shellfish are more likely to induce life-long anaphylactic hyperreactivity. In the first article in this issue, Ruiter and Shreffler discuss the molecular basis for allergenicity. Helminths and allergens uniquely induce Th2-biased immune responses. The authors review the literature on innate Th2 immune activation to glean novel insights into the immunogenic properties of food allergens. The allergic effector response is mediated by IgE, most commonly considered in the context of the mast cell cross-linking and degranulation induced by binding to its high-affinity receptor FceR1. However, as discussed by Berin, each of the three isotypes of immunoglobulin present at mucosal surfaces play a particular role in promoting tolerance or immunity to foods by facilitating antigen uptake. IgA, the dominant isotype, is secreted into the lumen and acts to prevent allergen from crossing the epithelial barrier. Antigen-specific IgA levels inversely correlate with clinical reactivity to food and aeroallergens. Conversely, IgG contributes to non-responsiveness to dietary antigen by facilitating antigen sampling. The neonatal Fc receptor transports antigen: IgG complexes from breast milk to induce tolerance to potential allergens early in life. By contrast, IgE-facilitated antigen delivery via CD23 contributes to clinical reactivity by delivering antigen:IgE complexes to allergic effector cells [7]. Food allergic patients do not present with a consistent set of complaints. Symptoms can range from transient urticaria or extend beyond the skin and gastrointestinal tract to the respiratory and cardiovascular collapse characteristic of a systemic anaphylactic response. Only some foods seem to trigger anaphylaxis; peanuts and tree nuts most commonly induce severe reactions, but there is currently no way to predict what kind of response will occur. A better understanding of allergic effector pathways may be helpful in predicting disease severity. Based on both murine model data and corroborative human studies, Hogan et al. suggest that intestinal mast cells play an important role in controlling the severity of food-induced anaphylaxis [8]. Two possible scenarios are presented: intestinal mast cells may lead to increased intestinal permeability and systemic antigen absorption, enabling systemic mast cell activation and potentiation of respiratory and cardiovascular collapse. Alternatively, in the presence of high intestinal mast cell numbers, mediators released in response to mast cell degranulation in the intestine may gain access to the systemic circulation and stimulate respiratory and cardiovascular collapse directly. This article is published as part of the Special Issue on Food Allergy [34:5].

Possible Anaphylaxis Due to Recombinant Factor VIIa Administration During Thoracic Aortic Surgery

Possible Anaphylaxis Due to Recombinant Factor VIIa Administration During Thoracic Aortic Surgery

Perioperative Anaphylaxis and the United States Perspective

Perioperative Anaphylaxis and the United States Perspective

Emodin, a naturally occurring anthraquinone derivative, suppresses IgE-mediated anaphylactic reaction and mast cell activation

The high-affinity receptor for IgE (FcɛRI)-mediated activation of mast cells plays an important role in allergic diseases such as asthma, allergic rhinitis and atopic dermatitis. Emodin, a naturally occurring anthraquinone derivative in oriental herbal medicines, has several beneficial pharmacologic effects, such as anti-cancer and anti-diabetic activities. However, the anti-allergic effect of emodin has not yet been investigated. To assess the anti-allergic activity of emodin, in vivo passive anaphylaxis animal model and in vitro mouse bone marrow-derived mast cells were used to investigate the mechanism of its action on mast cells. Our results showed that emodin inhibited degranulation, generation of eicosanoids (prostaglandin D 2 and leukotriene C 4), and secretion of cytokines (TNF-α and IL-6) in a dose-dependent manner in IgE/Ag-stimulated mast cells. Biochemical analysis of the FcɛRI-mediated signaling pathways demonstrated that emodin inhibited the phosphorylation of Syk and multiple downstream signaling processes including mobilization of intracellular Ca 2+ and activation of the mitogen-activated protein kinase, phosphatidylinositol 3-kinase, and NF-κB pathways. When administered orally, emodin attenuated the mast cell-dependent passive anaphylactic reaction in IgE-sensitized mice. Thus, emodin inhibits mast cell activation and thereby the anaphylactic reaction through suppression of the receptor-proximal Syk-dependent signaling pathways. Therefore, emodin might provide a basis for development of a novel anti-allergic drug.