Surface Of Mast Cells Research Articles

Dendritic cells give mast cells a nudge

Immunology Anaphylaxis is a life-threatening allergic reaction triggered after antigen-specific immunoglobulin E (IgE) antibodies bind to target allergens. These antibodies then cross-link IgE-specific Fc receptors on the surface of mast cells. The mast cells rapidly release inflammatory mediators, including histamine, resulting in smooth muscle contraction, vasodilation, and blood vessel leakage. Because mast cells are usually found in the perivascular abluminal surface of blood vessels, it has been unclear how blood-borne allergens can interact with them. Choi et al. used live intravital imaging of the mouse vasculature to show that a specialized subset of dendritic cells sample blood-borne antigens and relay them to mast cells on the surface of microvesicles (see the Perspective by Levi-Schaffer and Scheffel). IgE-bound mast cells then vigorously degranulate after contact with these microvesicles. Science , this issue p. [eaao0666][1]; see also p. [640][2] [1]: /lookup/doi/10.1126/science.aao0666 [2]: /lookup/doi/10.1126/science.aav4505

Tranexamic acid inhibits the plasma and non-irradiated skin markers of photoaging induced by long-term UVA eye irradiation in female mice

Photoaging can be induced by long-term ultraviolet (UV)A eye irradiation, but an ameliorating method for such photoaging is not known. In this study, we examined the effects of tranexamic acid (trans-4-aminomethylcyclohexanecarboxylic acid) on photoaging of the skin induced by UVA eye irradiation. We used the C57BL/6 j female mice and locally exposed their eyes to UVA at a dose of 110 kJ/m2 using an FL20SBLB-A lamp multiple times a week for one year. The plasma urocortin 2, β-endorphin, methionine enkephalin (OGF), and histamine content, as well as the expression of the corticotropin-releasing hormone receptor (CRHR) type 2, μ-opioid receptor, opioid growth factor receptor (OGFR), T-bet, and GATA3 increased in the mice subjected to UVA eye irradiation. However, the increased levels of urocortin 2, methionine enkephalin, histamine, OGFR, T-bet, and GATA3 were suppressed by tranexamic acid treatment. Conversely, the levels of β-endorphin and μ-opioid receptor increased with tranexamic acid treatment. In addition, the expression of the estrogen receptor-β on the surface of mast cells was increased by tranexamic acid. These results indicate that photoaging induced by UVA eye irradiation can be ameliorated by tranexamic acid through the regulation of hypothalamo-pituitary hormones. Furthermore, this ameliorative effect on photoaging may be due to an increase in estrogen receptor-β after tranexamic acid treatment.

Inhibitor for FcεRI expression on mast cell from Verbasucum thapsus L.

We found out 2′,3′-dihydroxypuberulin from South American medicinal plant, V. thapsus L., as a candidate of an anti-allergic lead which inhibits the expression of high-affinity receptor of IgE (FcεRI) on the surface of mast cells. Furthermore, the analysis of structure-activity relationship by using synthesized 2′,3′-dihydroxypuberulin analogs revealed that both hydroxy groups in the side chain and both of methyl moieties on phenolic hydroxy groups were crucial for potent activity, but absolute configuration of C-3′ position wasn’t. The active principle, 2′,3′-dihydroxypuberulin, was disclosed to down-regulate the mRNA level of β-chain of FcεRI, different from previous reported active natural product reducing γ-chain level.

Cryptotanshinone inhibits IgE‑mediated degranulation through inhibition of spleen tyrosine kinase and tyrosine‑protein kinase phosphorylation in mast cells.

Atopic dermatitis (AD) is a type of chronic skin inflammation and one of the most common relapsing allergic diseases, which presents with a severe rash and itchy skin lesions. The pathogenesis of AD is primarily associated with hyper‑activated mast cells, which makes them an effective treatment target. After cross‑linking the antigen/immunoglobulin (Ig) E complex binds to its high affinity receptor FcεRl on the surface of mast cells. The cells subsequently secrete excessive pro‑inflammatory mediators, including histamine and cytokines, which lead to pruritus and immune cell infiltration in the skin lesions. The present study screened natural compounds that have an inhibitory effect on IgE/antigen‑mediated secretory activity. It was revealed that cryptotanshinone (CRT), a natural compound extracted from SalviamiltiorrhizaBunge, had inhibitory effects on the IgE/antigen complex. The underlying mechanism by which CRT exerted an anti‑allergy/inflammatory function was investigated using rat basophilic leukaemia (RBL) cells for degranulation assays and a 1‑chloro‑2,4‑dinitrobenzene (DNCB)‑induced AD Balb/c mouse model for invivo study. CRT effectively mitigated the secretion of pro‑inflammatory cytokines, including tumor necrosis factor‑α and interleukin1β, as well as immune cell infiltration into skin lesions in a mouse model of AD‑like skin disease induced by dinitrochlorobenzene. The inhibitory effect of CRT on IgE‑mediated mast cell degranulation was mediated by the inhibition of tyrosine kinase‑dependent degranulation signalling pathways involving spleen tyrosine kinase and Lyn. The present study revealed CRT as an inhibitor of mast cell degranulation. Therefore, CRT may be considered for development as a therapeutic drug to treat IgE‑mediated skin diseases.

IL-13 is produced by tumor cells in breast implant–associated anaplastic large cell lymphoma: implications for pathogenesis

More than 500 women worldwide have developed a CD30+ T-cell lymphoma around breast implants, strongly suggesting a cause-and-effect relationship, and designated as breast implant-associated anaplastic large cell lymphoma (BIA-ALCL). The mechanism of lymphomagenesis is unknown. Recently, a bacterial biofilm containing gram-negative bacilli was discovered on the surface of breast implants associated with ALCL. We and others have described overexpression of the proto-oncogene JUNB and mutations of JAK1/2, TP53 and STAT3 in BIA-ALCL. Here we report that BIA-ALCL cell lines and anaplastic lymphoma cells in clinical specimens produce IL-13, the signature cytokine of allergic inflammation. Supporting the link of BIA-ALCL to allergic inflammation, lymphoma cells were often surrounded by eosinophils and mast cells, features typically absent in systemic ALCL. Because of the link of IL-13 to allergy, we looked for IgE and found it decorating the surface of mast cells and antigen-presenting follicular dendritic cells in capsules and lymph nodes infiltrated by anaplastic lymphoma cells, but not uninvolved capsules. Plasma cells within capsules and regional lymph nodes were identified as a possible source of IgE. Together, these findings suggest the hypothesis that an amplified immune response with features of a chronic allergic reaction in a susceptible patient underlies the pathogenesis of BIA-ALCL.

Inhibition of allergen‐mediated mast cell activation by rosemary extract (Rosmarinus officinalis L.)

The prevalence of allergic inflammatory disorders is increasing at an alarming rate, with 40–50% of school‐aged children suffering today and more than 25% of people living in a developed nation presently diagnosed or expected to develop, an allergic disease in their lifetime. This trend places a large economic burden on healthcare systems with $20B spent on treating these disorders in the USA in 2007. Mast cells are immune sentinels and a driving force in both normal and pathological contexts of inflammation. Allergen detection by the immune system results in production of allergen‐specific immunoglobulin E (IgE) antibodies. These antibodies bind to their high‐affinity receptor FcɛRI, which is constitutively expressed on the surface of mast cells. Crosslinking of FcɛRI by allergen‐bound IgE antibodies leads to mast cell degranulation (e.g. histamine) resulting in an early phase response, and the release of newly synthesized pro‐inflammatory mediators, contributing to a late phase response. The mitogen‐activated protein kinase (MAPK) family and, nuclear factor‐κ‐light‐chain‐enhancer of activated B cells (NF‐κB) pathways have been established to be driving mechanisms behind mast cell‐induced inflammation. Rosemary extract (RE) is rich in polyphenols, including rosmarinic acid (RA), carnosic acid (CA), and carnosol (CO), which have been shown to inhibit the MAPK and NF‐κB pathways in other cellular contexts in vitro and in in vivo animal models. However, the effect of these polyphenols on mast cell activation and degranulation has not been explored. Therefore, the aim of this study was to evaluate the potential of RE in modulating mast cell activation and FcɛRI signaling via these pathways toward understanding the mechanism of action and functional outcomes. Mast cells were sensitized with anti‐TNP IgE and were stimulated with the cognate allergen (TNP‐BSA) under stem cell factor (SCF) potentiation, and treated with 0 – 25 μg/mL RE. Samples were then collected for β‐hexosaminidase assay, quantitative polymerase chain reaction (qPCR), enzyme‐linked immunosorbent assay (ELISA) and, western blotting analysis. The β‐hexosaminidase assay demonstrated that RE treatment inhibited mast cell degranulation dose‐dependently to a maximum (down to 15% of control) at 25 μg/mL (p<0.001) RE. qPCR analysis showed that RE treatment at 25 μg/mL resulted in decreased gene expression of IL6 at both 60 and 120 mins (p<0.05), IL13 at 120 mins (p<0.05), TNF at 120 mins (p<0.05), CCL1 at both 60 (p<0.01) and 120 mins (p<0.05), CCL3 at both 60 and 120 minutes (p<0.05), and Rcan1 at 120 mins (p<0.05). ELISA analysis further supported the qPCR data showing decreases in pro‐inflammatory IL‐6 at 12 hrs (p<0.05) and TNF at 24 hrs (p<0.05). Western blot analysis demonstrated that RE treatment at both 5 and 25 μg/mL inhibited phosphorylation of p38‐MAPK at 5 mins. This work enhances our current understanding of mast cell functional modulation, mast cell signaling, and mechanistic activities of RE with relevance to innate defences and allergy.Support or Funding InformationSupported by the Natural Sciences and Engineering Research Council of Canada (NSERC); Canada Foundation for Innovation (CFI); Government of Ontario; and Brock University.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Two Cases of Atopic Dermatitis that Healed Completely after Several Intradermal Injections with Non-Specific Antigen Preparation

Mutual exchanges between specific and non-specific antibody molecules on receptors on the surface of mast cells should take place after an accumulation of non-specific antibodies in the patients’ bodies. These exchanges will bring about decompositions of combinations of mast cells and specific antibodies. These decompositions equal eliminations of causes of allergic diseases.

Timescale Separation of Positive and Negative Signaling Creates History-Dependent Responses to IgE Receptor Stimulation

The high-affinity receptor for IgE expressed on the surface of mast cells and basophils interacts with antigens, via bound IgE antibody, and triggers secretion of inflammatory mediators that contribute to allergic reactions. To understand how past inputs (memory) influence future inflammatory responses in mast cells, a microfluidic device was used to precisely control exposure of cells to alternating stimulatory and non-stimulatory inputs. We determined that the response to subsequent stimulation depends on the interval of signaling quiescence. For shorter intervals of signaling quiescence, the second response is blunted relative to the first response, whereas longer intervals of quiescence induce an enhanced second response. Through an iterative process of computational modeling and experimental tests, we found that these memory-like phenomena arise from a confluence of rapid, short-lived positive signals driven by the protein tyrosine kinase Syk; slow, long-lived negative signals driven by the lipid phosphatase Ship1; and slower degradation of Ship1 co-factors. This work advances our understanding of mast cell signaling and represents a generalizable approach for investigating the dynamics of signaling systems.

Cationic liposomes suppress intracellular calcium ion concentration increase via inhibition of PI3 kinase pathway in mast cells

Cationic liposomes are commonly used as vectors to effectively introduce foreign genes (antisense DNA, plasmid DNA, siRNA, etc.) into target cells. Cationic liposomes are also known to affect cellular immunocompetences such as the mast cell function in allergic reactions. In particular, we previously showed that the cationic liposomes bound to the mast cell surface suppress the degranulation induced by cross-linking of high affinity IgE receptors in a time- and dose-dependent manner. This suppression is mediated by impairment of the sustained level of intracellular Ca2+ concentration ([Ca2+]i) via inhibition of store-operated Ca2+ entry (SOCE). Here we study the mechanism underlying an impaired [Ca2+]i increase by cationic liposomes in mast cells. We show that cationic liposomes inhibit the phosphorylation of Akt and PI3 kinases but not Syk and LAT. As a consequence, SOCE is suppressed but Ca2+ release from endoplasmic reticulum (ER) is not. Cationic liposomes inhibit the formation of STIM1 puncta, which is essential to SOCE by interacting with Orai1 following the Ca2+ concentration decrease in the ER. These data suggest that cationic liposomes suppress SOCE by inhibiting the phosphorylation of PI3 and Akt kinases in mast cells.

Role of Mast Cells in Regulation of T Cell Responses in Experimental and Clinical Settings.

Mast cells secrete a wide spectrum of stored or newly synthesized pro-inflammatory, anti-inflammatory, and/or immunosuppressive mediators and express several costimulatory and inhibitory surface molecules. Mast cells finely tune activities of T cells, B cells, and regulatory cells and effectively contribute to the development of different T cell-associated responses by influencing their recruitment, activation, proliferation, and differentiation. The interaction between mast cells and T cells, with regard to cellular functionality and immune responses, can be assessed in both activating and inhibitory regulations. While Th2 cytokines, including IL-5 and IL-9, stimulate stem cell factor (SCF)-dependent proliferation of mast cells, Th1 cytokine IFN-γ suppresses SCF-mediated differentiation of mast cell progenitors. Mast cell mediators such as CCL5 have a role in the recruitment of CD8+ T cells to viral infection sites where their ability in clearance of viral reservoirs is needed. The capacity of mast cells in presenting antigens by classes I and II MHC molecules to CD4+ and CD8+ T cells respectively is considered one of the main antigen-dependent interactions of mast cells with T cells. Interestingly, Tregs recruit mast cells to different sites through secretion of IL-9, while the OX40L (expressed on mast cell)-OX40(expressed on T cell) interaction inhibits the extent of the mast cell degranulation. Recently, the capability of exosomes to carry regulatory receptors of the mast cell surface and their role in T cell activation has been investigated. Functional interplay between mast cells and T cell subsets has been suggested primarily by investigating their co-localization in inflamed tissues and involvement of mast cells in autoimmune diseases. In this review, the interactions of mast cells with T cells are reviewed in cell-to-cell, cytokine, and exosome categories.

Extensive protein hydrolyzation is indispensable to prevent IgE-mediated poultry allergen recognition in dogs and cats

BackgroundThe central premise for the commercialization of diets with hydrolyzed ingredients is that the small-sized digested peptides would be unable to crosslink allergen-specific IgE at the surface of tissue mast cells and induce their degranulation. Evidence for the validity of this concept to diagnose food allergies in dogs and cats is limited, however. Our objectives were to study the recognition of standard and variably hydrolyzed poultry extracts by sera from dogs and cats with elevated chicken-specific serum IgE.ResultsForty sera from dogs and 40 from cats with undetectable, low, medium or high serum levels of chicken-specific IgE were tested by ELISA on plates coated with the positive controls chicken, duck and turkey meat extracts and the negative controls beef meat (dogs) or wheat (cats). Plates were also coated with a non-hydrolyzed chicken meal, and mildly- or extensively-hydrolyzed poultry feather extracts. The frequencies of dogs with positive IgE against the various extracts were: chicken meat: 100%, duck and turkey meats: 97%, beef meat: 3%, non-hydrolyzed chicken meal: 73%, mildly-hydrolyzed poultry feathers: 37% and extensively-hydrolyzed poultry feathers: 0%. For cats, these respective percentages were (with wheat replacing beef as a negative control): 100, 84, 97, 7, 7, 0 and 0%. To detect any allergenic cross-reactivity between poultry meat-based and feather hydrolysate-derived extracts, an IgE ELISA inhibition was also done. Ten canine sera with the highest level of anti-poultry IgE in the previous experiment were incubated overnight with a previously optimized 50 μg amount of each of the extracts used above. We performed ELISA on plates coated with chicken, duck or turkey meats with or without inhibitors. The median inhibition percentages after incubation with the non-hydrolyzed chicken meal were ~22%, with the mildly-hydrolyzed poultry feathers: 14–22%, and those with the extensively-hydrolyzed poultry feathers: 5 to 10%; the last inhibition level was similar to that of the beef meat negative control.ConclusionsAltogether, these results suggest that an extensive—but not partial—hydrolyzation of the poultry feather extract is necessary to prevent the recognition of allergenic epitopes by poultry-specific IgE.

Long-term effects: Galectin-1 and specific immunotherapy for allergic responses in the intestine.

Mast cell activation interferes with the effects of allergen-specific immunotherapy (SIT). Galectin-1 (Gal-1) is capable of regulating immune cells' functions. This study tests the hypothesis that administration of Gal-1 promotes and prolongs the efficacy of SIT via suppressing mast cell activation. An intestinal allergy mouse model was developed. The coadministration of SIT and Gal-1 on suppression of the allergic responses, prevention of mast cell activation, and generation of antigen-specific regulatory T cells (Treg) in the intestine was observed in sensitized mice. The coadministration of Gal-1 and SIT markedly suppressed the allergic responses in the mouse intestine vs the use of either SIT alone or Gal-1 alone. The Gal-1 binds to the IgE/FcɛRI complexes on the surface of mast cells to prevent mast cell activation during SIT. Gal-1 promoted the SIT-generated allergen-specific Tregs in the intestine of sensitized mice. Coadministration of Gal-1 and SIT significantly enhanced the efficacy of immunotherapy in suppressing allergic responses in the intestine, which lasted for at least for 12months. Long-term effects of specific immunotherapy on intestinal allergy can be achieved with Gal-1/SIT therapy by inhibiting mast cell activation and facilitating Treg development.

Epidemiology, Mechanisms, and Diagnosis of Drug-Induced Anaphylaxis.

Anaphylaxis is an acute, life-threatening, multisystem syndrome resulting from the sudden release of mediators by mast cells and basophils. Although anaphylaxis is often under-communicated and thus underestimated, its incidence appears to have risen over recent decades. Drugs are among the most common triggers in adults, being analgesics and antibiotics the most common causal agents. Anaphylaxis can be caused by immunologic or non-immunologic mechanisms. Immunologic anaphylaxis can be mediated by IgE-dependent or -independent pathways. The former involves activation of Th2 cells and the cross-linking of two or more specific IgE (sIgE) antibodies on the surface of mast cells or basophils. The IgE-independent mechanism can be mediated by IgG, involving the release of platelet-activating factor, and/or complement activation. Non-immunological anaphylaxis can occur through the direct stimulation of mast cell degranulation by some drugs, inducing histamine release and leading to anaphylactic symptoms. Work-up of a suspected drug-induced anaphylaxis should include clinical history; however, this can be unreliable, and skin tests should also be used if available and validated. Drug provocation testing is not recommended due to the risk of inducing a harmful reaction. In vitro testing can help to confirm anaphylaxis by analyzing the release of mediators such as tryptase or histamine by mast cells. When immunologic mechanisms are suspected, serum-sIgE quantification or the use of the basophil activation test can help confirm the culprit drug. In this review, we will discuss multiple aspects of drug-induced anaphylaxis, including epidemiology, mechanisms, and diagnosis.

THE STUDY OF THE INFLUENCE OF MODEL MEAT SYSTEMS ON THE ALLERGIC IMMUNE RESPONSE IN VIVO

This article presents the results of studying the effect of homogeneous model meat systems produced using enzyme preparation containing fungal protease and microbiological starter culture of Lactobacillus plantarum on the allergic reactions within specific immunity in vivo. According to the results, it is established that experimental products have no negative effect on the clinical parameters of laboratory animals. During the experiment, with the introduction of experimental products into diet, the dynamics of body weight changes in all groups of animals was positive. At the end of the experiment, there were smaller increase in the weight of rats and lower values of weight gain (Group 1 — 14.0 %, Group 2 — 15.9 %, Group 3 — 20.2 %). This is possibly due to the adaptation processes occurring in response to introduction of meat systems into the diet, which confirms the leveling of the daily weight gain of experimental and intact animals since the 16th day of the experiment. According to the results of clinical blood analysis of the animals consuming experimental products, an increase is detected in leukocytes and lymphocytes by up to 18 %; in granulocytes by up to 35 %; and in monocytes by up to 8 %; in hemoglobin concentration, hematocrit and mean corpuscular hemoglobin concentration by more than 3 %; in red cell distribution width and mean corpuscular volume by up to 2 %, in comparison with intact animals. The correlation of these data with ELISA parameters for serum of experimental animals (histamine and immunoglobulin E) allowed to suggest the expression of reaginic antibodies and interaction on the surface of basophils and mast cells, which led to the degranulation and release (increase) of histamine, as a vasoactive factor, by 40 % compared with intact animals. The overall conclusion of the studies is that experimental model meat systems may trigger the activation of specific immune responses in laboratory animals. This is possibly due to protease-mediated formation of greater amount of indigestible polypeptides and peptides that invoke local adaptation responses.

Acute granulocyte macrophage-colony stimulating factor treatment modulates neuroinflammatory processes and promotes tactile recovery after spinal cord injury

Neuroinflammation is known to play a key role in the prognosis of functional recovery after spinal cord injury (SCI). The involvement of microglial and mast cells in early and late stages of inflammation has been receiving increasing attention. This study was aimed at determining the influence of a pro-inflammatory cytokine, the granulocyte macrophage-colony stimulating factor (GM-CSF), on microglia and mast cell activation, glial scar formation and functional recovery following SCI. Rats were randomly injected with saline or GM-CSF one hour after a C4–C5 medio-lateral hemisection. To assess functional impairment and recovery, the rats were subjected to sensorimotor tasks for one month. Then, responses evoked by forepaw stimulation in the primary somatosensory cortex were recorded. We also quantified the changes in GM-CSF, IL-1β, IL-6 and BDNF levels, the gliosis and lesion volume as well as microglial and mast cell density, and mast cell surface. Our findings show that GM-CSF promotes cortical reactivation and recovery of tactile abilities, whereas it does not influence motor performances. A transient decrease in pro-inflammatory cytokines after GM-CSF treatment was also observed, whereas the endogenous GM-CSF level was unchanged. While the beneficial role of GM-CSF in reducing glial scar is confirmed, our findings reveal that neuroinflammatory events mediated by microglial and mast cells as well as the alteration of IL-1β and IL-6 levels are paralleled with an improvement in tactile recovery. These mechanisms could limit the duration and intensity of homeostatic imbalance and promote the plasticity of spared tissues.

The hematopoietic cell-specific transcription factor PU.1 is critical for expression of CD11c.

PU.1 is a hematopoietic cell-specific transcription factor belonging to the Ets family, which plays an important role in the development of dendritic cells (DCs). CD11c (encoded by Itgax) is well established as a characteristic marker of hematopoietic lineages including DCs. In the present study, we analyzed the role of PU.1 (encoded by Spi-1) in the expression of CD11c. When small interfering RNA (siRNA) for Spi-1 was introduced into bone marrow-derived DCs (BMDCs), the mRNA level and cell surface expression of CD11c were dramatically reduced. Using reporter assays, the TTCC sequence at -56/-53 was identified to be critical for PU.1-mediated activation of the promoter. An EMSA showed that PU.1 directly bound to this region. ChIP assays demonstrated that a significant amount of PU.1 bound to this region on chromosomal DNA in BMDCs, which was decreased in LPS-stimulated BMDCs in accordance with the reduced levels of mRNAs of Itgax and Spi-1, and the histone acetylation degree. Enforced expression of exogenous PU.1 induced the expression of the CD11c protein on the cell surface of mast cells, whereas control transfectants rarely expressed CD11c. Quantitative RT-PCR also showed that the expression of a transcription factor Irf4, which is a partner molecule of PU.1, was reduced in PU.1-knocked down BMDCs. IRF4 transactivated the Itgax gene in a synergistic manner with PU.1. Taken together, these results indicate that PU.1 functions as a positive regulator of CD11c gene expression by directly binding to the Itgax promoter and through transactivation of the Irf4 gene.

Immunology of Bee Venom.

Bee venom is a blend of biochemicals ranging from small peptides and enzymes to biogenic amines. It is capable of triggering severe immunologic reactions owing to its allergenic fraction. Venom components are presented to the T cells by antigen-presenting cells within the skin. These Th2 type T cells then release IL-4 and IL-13 which subsequently direct B cells to class switch to production of IgE. Generating venom-specific IgE and crosslinking FcεR1(s) on the surface of mast cells complete the sensitizing stage in allergic individuals who are most likely to experience severe and even fatal allergic reactions after being stung. Specific IgE for bee venom is a double-edged sword as it is a powerful mediator in triggering allergic events but is also applied successfully in diagnosis of the venom allergic patient. The healing capacity of bee venom has been rediscovered under laboratory-controlled conditions using animal models and cell cultures. The potential role of enzymatic fraction of bee venom including phospholipase A2 in the initiation and development of immune responses also has been studied in numerous research settings. Undoubtedly, having insights into immunologic interactions between bee venom components and innate/specific immune cells both locally and systematically will contribute to the development of immunologic strategies in specific and epitope-based immunotherapy especially in individuals with Hymenoptera venom allergy.

2-Hydroxy-3-methoxybenzoic acid attenuates mast cell-mediated allergic reaction in mice via modulation of the FcεRI signaling pathway.

Mast cells are important effector cells in immunoglobulin (Ig) E-mediated allergic reactions such as asthma, atopic dermatitis and rhinitis. Vanillic acid, a natural product, has shown anti-oxidant and anti-inflammatory activities. In the present study, we investigated the anti-allergic inflammatory effects of ortho-vanillic acid (2-hydroxy-3-methoxybenzoic acid, o-VA) that was a derivative of vanillic acid isolated from Amomum xanthioides. In mouse anaphylaxis models, oral administration of o-VA (2, 10, 50 mg/kg) dose-dependently attenuated ovalbumin-induced active systemic anaphylaxis and IgE-mediated cutaneous allergic reactions such as hypothermia, histamine release, IgE production and vasodilation; administration of o-VA also suppressed the mast cell degranulator compound 48/80-induced anaphylaxis. In cultured mast cell line RBL-2H3 and isolated rat peritoneal mast cells in vitro, pretreatment with o-VA (1-100 μmol/L) dose-dependently inhibited DNP-HSA-induced degranulation of mast cells by decreasing the intracellular free calcium level, and suppressed the expression of pro-inflammatory cytokines TNF-α and IL-4. Pretreatment of RBL-2H3 cells with o-VA suppressed DNP-HSA-induced phosphorylation of Lyn, Syk, Akt, and the nuclear translocation of nuclear factor-κB. In conclusion, o-VA suppresses the mast cell-mediated allergic inflammatory response by blocking the signaling pathways downstream of high affinity IgE receptor (FcεRI) on the surface of mast cells.

Mast cell and eosinophil surface receptors as targets for anti-allergic therapy

Abstract Allergy is the host immune response towards harmless substances, called allergens. Allergic diseases comprise allergic asthma, allergic rhinitis, allergic conjunctivitis, atopic dermatitis, and food allergy. While some drugs counteract the symptoms and the inflammation arising from allergy, no completely effective and acceptable side effect free drug has been developed as yet. Moreover, severe asthma and atopic dermatitis are classified as unmet clinical needs. Mast cells and eosinophils are the main effector cells of the allergic response and thus, must be the first cells targeted to impede the allergic inflammation symptoms and evolution. The presence on mast cells and eosinophils of several surface receptors with either activating or inhibitory functions indicates the possibility of their pharmacological targeting. This review deals with some of the receptors expressed on mast cells and eosinophils and their ligand(s). Some receptors have already been exploited as drug targets and others can be feasibly utilized as novel targets for anti-allergic therapy.

Characterization of the potential allergenicity of irradiated bovine α-lactalbumin in a BALB/c mouse model

Bovine α-lactalbumin (ALA) is a known food allergen present in milk to induce anaphylaxis. A previous study demonstrated that irradiated ALA (iALA) decreased the IgE-binding properties and weakened the degranulation capacity of basophils in vitro. The present study aimed to further assess the potential allergenicity of iALA in vivo in a BALB/c mouse model. The mice (n = 10/group) were intragastrically sensitized and orally challenged with either iALA or ALA using cholera toxin as adjuvant. In contrast to the ALA group, the iALA group did not show anaphylactic shock symptoms. A tendency toward decreased serum allergen-specific IgG/IgG1/IgE levels, plasma histamine levels and mast cell protease-1 (mMCP-1) concentrations in the iALA group were also observed, accompanied by a decrease in Th2-related cytokine levels and an increase of IFN-γ production in spleen cell cultures. Moreover, the peritoneal mast cell surface expression of FcεRI and peripheral blood basophil CD200R+ expression were decreased by 64.3% and 35.19%, respectively. Conversely, the percentage of CD4+CD25+Foxp3+ regulatory T cells increased in the iALA group. All of these findings indicated that iALA induces a shift toward the Th1 response, which ultimately reduces its potential allergenicity.