Release Of Allergic Mediators Research Articles

Coconut milk allergenicity: Insight into reducing the affinity of coconut globulin to immunoglobulin E by atmospheric cold plasma

Atmospheric cold plasma (ACP) presents a promising method for the sterilization of coconut milk and exhibits a modifying effect on coconut globulin (CG), the primary allergen in coconut milk. This study investigated the potential role of ACP treatment in mitigating the allergenic properties of coconut milk by examining changes in protein structure. ACP treatment induced structural alterations in CG, disrupting binding sites with immunoglobulin E (IgE). Consequently, this led to a reduction in the affinity between CG and IgE, evidenced by a decrease in Ka from 2.17 × 104/M to 0.64 × 104/M, thereby diminishing IgE-mediated allergic reactions. The findings from allergenic and cellular models further corroborated that ACP treatment decreased the allergenicity of CG by 55.18%, while inhibiting degranulation and the release of allergic mediators. This study presents an innovative methodology for producing hypoallergenic coconut milk, thereby expanding the applicability of ACP technology within the food industry.

Aspalathin, a Primary Rooibos Flavonoid, Alleviates Mast Cell-Mediated Allergic Inflammation by the Inhibition of FcεRI Signaling Pathway.

Mast cells are primary cells initiating allergic inflammation by the release of various allergic mediators, such as histamine and pro-inflammatory cytokines. Aspalathin (ASP) is the predominant flavonoid found exclusively in rooibos, an herb that has been traditionally used in allergy relief therapy. In the present study, we investigated the beneficial effects of ASP on mast cell-mediated allergic inflammation. For in vivo study, two well-known mast cell-mediated local and systemic allergic inflammation mouse models were used: passive cutaneous anaphylaxis (PCA) and active systemic anaphylaxis mouse models (ASA). Oral administration of ASP dose-dependently suppressed immunoglobulin (Ig)E-mediated PCA responses evidenced by Evans blue extravasation, ear thickening, and mast cell degranulation. ASP also significantly mitigated ovalbumin-induced ASA responses, including hypothermia, histamine secretion, and the production of IgE and interleukin-4. Notably, ASP was more effective in suppressing allergic inflammation than nothofagin, another prominent flavonoid known as an anti-allergic component of rooibos. The regulatory mechanism of mast cell activation by ASP was clarified using mast cell line and primary cultured mast cells (RBL-2H3 and mouse bone marrow-derived mast cells). ASP reduced IgE-stimulated mast cells degranulation and intracellular calcium influx by the inhibition of FcεRI signaling pathway (Lyn, Fyn, and Syk). Moreover, ASP reduced pro-inflammatory cytokine expressions by inhibiting two major transcription factors, nuclear factor of activated T cells and nuclear factor-κB. Collectively, we proposed that ASP could be a potential therapeutic candidate for the treatment of mast cell-mediated allergic inflammatory diseases.

Ethanol Extract of Ampelopsis brevipedunculata Rhizomes Suppresses IgE-Mediated Mast Cell Activation and Anaphylaxis.

More than 20% of the world's population suffers from allergic diseases, including allergic asthma, rhinitis, and atopic dermatitis that severely reduce the patient's quality of life. The treatment of allergy has been developed, but there are still unmet needs. Ampelopsis brevipedunculata (Maxim.) Trautv. is a traditional medicinal herb with beneficial bioactivities, such as antioxidant, anti-hypertension, anti-viral, anti-mutagenic, and skin and liver (anti-hepatotoxic) protective actions. However, its anti-allergic effect has not been addressed. This study designed to investigate the pharmacological effect of an ethanol extract of A. brevipedunculata rhizomes (ABE) on mast cell and anaphylaxis models. For in vivo studies, we used ovalbumin-induced active systemic anaphylaxis (ASA) and immunoglobulin (Ig) E-mediated passive cutaneous anaphylaxis (PCA) models. In ASA model, oral administration of ABE (1, 10, and 100 mg/kg) attenuated the anaphylactic responses, such as hypothermia, serum histamine, and IgE productions. In PCA model, ABE also suppressed the plasma extravasation and swelling. The underlying mechanisms of action were identified in various mast cell types. In vitro, ABE (10, 30, and 60 µg/mL) inhibited the release of essential allergic mediators, such as histamine and β-hexosaminidase, in a concentration-dependent manner. ABE prevented the rapid increase in intracellular calcium levels induced by the DNP-HSA challenge. In addition, ABE downregulated the tumor necrosis factor-α and interleukin-4 by suppressing the activation of nuclear factor-κB. Collectively, this study is the first to identify the anti-allergic effect of ABE, suggesting that ABE is a promising candidate for treating allergic diseases.

Myricetin served as antagonist for negatively regulate MRGPRX2 mediated pseudo-allergic reactions through CD300f/SHP1/SHP2 phosphorylation.

Mas-related G protein-coupled receptor X2 (MRGPRX2) plays a vital role in mast cells (MCs) degranulation and pseudo-allergic reactions. Leukocyte mono-immunoglobulin-like receptor 3 (CD300f) can negatively regulate MCs degranulation. Identification of drug candidates which target CD300f represents a promising prospect in drug development. Myricetin is widely distributed in plants and has been reported to inhibit allergic reactions in OVA-induced murine models. This study aims to determine whether myricetin can activate CD300f to arrest MCs degranulation mediated by MRGPRX2. Myricetin inhibited the allergic mediator and cytokine release triggered by MRGPRX2 in vivo and in vitro. Under C48/80 stimulation, the release of β-hexosaminidase, TNF-α, IL-8 and MCP-1 in CD300f knockdown in LAD2 cells was significantly increased compared with NC-LAD2 cells. Myricetin displayed good structural affinity (KD=7.21×10-5) with CD300f by SPR. Molecular docking results showed that hydrogen bonds were formed between myricetin and CD300f, indicating high binding ability (5.6653). Myricetin can upregulate the phosphorylation of SHP-1 and SHP-2 and dephosphorylation in the MRGPRX2 signaling pathway, involving PLCγ1, AKT, P38, and ERK1/2. In the present study, myricetin is identified as an exogenous ligand for CD300f, which negatively regulates MRGPRX2-mediated MCs activation via CD300f to inhibit MCs degranulation and pseudo-allergic reactions.

Strain matters in mouse models of peanut-allergic anaphylaxis: Systemic IgE-dependent and Ara h 2-dominant sensitization in C3H mice.

Peanut allergy accounts for the majority of food-induced hypersensitivity reactions and can lead to lethal anaphylaxis. Animal models can provide an insight into the immune mechanisms responsible for sensitization and allergic anaphylaxis. However, different mouse strains and sensitization protocols can influence the successful development of a peanut allergic mouse model. We aimed at developing a systemic anaphylaxis model of peanut allergy that resembles human anaphylaxis. We compared the immunological and clinical responses in genetically different mouse strains. Female BALB/c, C57BL/6, and C3H mice were intraperitoneally sensitized and later challenged with peanut proteins. Allergen-specific serology was done by ELISA, and anaphylaxis was evaluated by monitoring changes in body temperature upon systemic challenge. Sensitization to peanut was successful in C3H mice and triggered production of allergen-specific antibodies, cytokines and anaphylaxis. Allergic reactions were characterized by the release of allergic mediators and by changes in leukocyte populations in blood and in the peritoneal cavity. Among the identified major peanut allergens, Ara h 2 showed the strongest anaphylactic potential. Much lower or no trigger of peanut-specific antibodies was observed in BALB/c and C57BL/6 mice, which experienced no hypersensitivity reactions. Mouse strain matters for testing of peanut protein allergens. We identified C3H mice as a suitable strain for the development of a mouse model of peanut-allergic anaphylaxis. Pre-clinical, humoural and cellular responses resembled the responses observed in human patients. The described model can be useful for further studies on peanut allergy and for the development of new therapeutic strategies.

Extracellular Ca2+ aggravates IgE-induced allergic reaction in mast cells through GPRC6A, a novel family C G-protein-coupled receptor

AimsAs an essential indicator of allergic reactions, mast cell (MC) activation involves FcεRI-mediated signaling and the release of allergic mediators. In FcεRI signaling, Ca2+ is located at the intersection of multiple cellular signaling pathways. However, the effect of extracellular Ca2+ (exCa2+) on MCs during anaphylaxis remains unclear, along with its exact mechanisms. Therefore, we sought to determine whether and how elevated exCa2+ amplifies allergic reactions. Main methodsIn vitro experiments used immunoglobulin E (IgE)/antigen (Ag)-induced activation of rat and mouse MCs in vitro. The levels of MC degranulation mediators were used to evaluate the effect of exCa2+. In vivo experiments used MC-mediated passive systemic anaphylaxis (PCA) Balb/c mice. After stimulation, anaphylaxis indexes such as rectal temperature and allergic symptom score were detected. Key findingsIn vitro experiments revealed that exCa2+ is a stimulus signal for the aggravation of allergic reactions in MCs. When antagonists or siRNA inhibited GPRC6, MCs released fewer inflammatory mediators. Moreover, in vivo experiments confirmed in vitro results. Allergic symptoms were alleviated by antagonists NPS2143 in PCA mice, demonstrating that exCa2+ aggravates allergic reactions through GPRC6A. SignificanceOur study provides an essential theoretical basis for targeting Ca2+ and GPRC6A as therapeutic options for allergies.

Chemokines and chemokine receptors in allergic rhinitis: from mediators to potential therapeutic targets.

Allergic rhinitis (AR) is an immune-mediated inflammatory condition characterized by immune cell infiltration of the nasal mucosa, with symptoms of rhinorrhea, sneezing, nasal obstruction, and itchiness. Currently, common medication for AR is anti-inflammatory treatment including intranasal steroids, oral, or intranasal anti-histamines, and immunotherapy. These strategies are effective to the majority of patients with AR, but some patients under medication cannot achieve symptom relieve and suffer from bothersome side effects, indicating a demand for novel anti-inflammatory treatment as alternatives. Chemokines, a complex superfamily of small, secreted proteins, were initially recognized for their chemotactic effects on various immune cells. Chemokines constitute both physiological and inflammatory cell positioning systems and mediate cell localization to certain sites via interaction with their receptors, which are expressed on responding cells. Chemokines and their receptors participate in the sensitization, early phase response, and late phase response of AR by promoting inflammatory cell recruitment, differentiation, and allergic mediator release. In this review, we first systemically summarize chemokines and chemokine receptors that are important in AR pathophysiology and then discuss potential strategies targeting chemokines and their receptors for AR therapy.

MOLECULAR DOCKING AS POTENTIAL ANTI-INFLAMMED QUERSETIN OF MORINGA LEAVES (Moringa oleifera L.) WITH AUTODOCK-VINA

Inflammation is a response to tissue injury that involves a physiological process in the form of activation of the cyclooxygenase (COX) enzyme which has two isoforms, namely the cyclooxygenase-1 (COX-1) and cyclooxygenase-2 (COX-2) enzymes. The leaves of Moringa (Moringa oleifera L.) contain quercetin which has shown anti-inflammatory activity by blocking the synthesis and release of histamine and other inflammatory allergic mediators. This study aims to determine the role of quercetin in Moringa leaves as an anti-inflammatory ligand 6 COX cyclooxigenase-2 (COX-2) with the application of autodock vina. The method used was that all ligands were docking molecularly using the AutoDock Vina program. The results obtained are the binding affinity (kcal / mol) of the ligand to protein. The Ligplot + program is used to visualize the 3D conformation of molecules and ligand-protein interactions. The hardware used by ASUS notebooks with Windows 10 64 bit specifications. Based on molecular docking, quercetin has a potential activity as an anti-inflammatory because it has affinity and forms hydrogen cox 6 bonds in-silico and can be continued with in vitro activity tests in the laboratory to get results as anti-inflammatory.

Streptococcal H2O2 inhibits IgE-triggered degranulation of RBL-2H3 mast cell/basophil cell line by inducing cell death.

Mast cells and basophils are central players in allergic reactions triggered by immunoglobulin E (IgE). They have intracellular granules containing allergic mediators (e.g., histamine, serotonin, inflammatory cytokines, proteases and β-hexosaminidase), and stimulation by IgE-allergen complex leads to the release of such allergic mediators from the granules, that is, degranulation. Mast cells are residents of mucosal surfaces, including those of nasal and oral cavities, and play an important role in the innate defense system. Members of the mitis group streptococci such as Streptococcus oralis, are primary colonizers of the human oral cavity. They produce hydrogen peroxide (H2O2) as a by-product of sugar metabolism. In this study, we investigated the effects of streptococcal infection on RBL-2H3 mast cell/basophil cell line. Infection by oral streptococci did not induce degranulation of the cells. Stimulation of the RBL-2H3 cells with anti-dinitrophenol (DNP) IgE and DNP-conjugated human serum albumin triggers degranulation with the release of β-hexosaminidase. We found that S. oralis and other mitis group streptococci inhibited the IgE-triggered degranulation of RBL-2H3 cells. Since mitis group streptococci produce H2O2, we examined the effect of S. oralis mutant strain deficient in producing H2O2, and found that they lost the ability to suppress the degranulation. Moreover, H2O2 alone inhibited the IgE-induced degranulation. Subsequent analysis suggested that the inhibition of degranulation was related to the cytotoxicity of streptococcal H2O2. Activated RBL-2H3 cells produce interleukin-4 (IL-4); however, IL-4 production was not induced by streptococcal H2O2. Furthermore, an in vivo study using the murine pollen-induced allergic rhinitis model suggested that the streptococcal H2O2 reduces nasal allergic reaction. These findings reveal that H2O2 produced by oral mitis group streptococci inhibits IgE-stimulated degranulation by inducing cell death. Consequently, streptococcal H2O2 can be considered to modulate the allergic reaction in mucosal surfaces.

Inhibition of Allergic Reactivity through Targeting FcεRI-Bound IgE with Humanized Low-Affinity Antibodies.

Options for effective prevention and treatment of epidemic allergic diseases remain limited, and particularly so for IgE-mediated food allergies. We previously found that mouse low-affinity anti-human IgE mAbs with KD in the 10-6-10-8 M range were capable of blocking allergic reactivity without triggering immediate allergic mediator release. In this study, we humanized three parent low affinity allergic response inhibitor (LARI) mouse anti-human IgE mAbs and characterized their biological and immunological features, refined the lead candidate for further clinical development, examined their safety profiles, determined their therapeutic efficiency, and explored the mechanism of action potentially responsible for their therapeutic effects. LARI profoundly blocked cat- and peanut-allergic IgE-mediated basophil activation, inhibited acute release of both prestored and newly synthesized mediator from human mast cells, suppressed peanut-specific IgE-mediated passive cutaneous anaphylaxis, and attenuated dansyl IgE-mediated systemic anaphylaxis in human FcεRIα transgenic mice. Safety testing demonstrated that concentrations of LARI well above therapeutic levels failed to trigger immediate release of prestored and newly synthesized allergic mediators, failed to promote robust cytokine/chemokine production from allergic effector cells, and did not elicit allergic reactivity in an animal model of cutaneous and systemic anaphylaxis. Mechanistic studies revealed that LARI downregulated surface FcεRI receptors and IgE via internalization of the IgE/FcεRI, promoted a partial mediator depletion pathway leading to slow release of small amount of mediators, and functioned as a partial antagonist to inhibit FcεRI signaling phosphorylation of Syk, Akt, Erk, and p38 MAPK. These studies demonstrate that targeting surface-bound IgE with LARI profoundly suppresses human allergic reactivity while displaying an excellent safety profile.

Mast Cell Activation and Microtubule Organization Are Modulated by Miltefosine Through Protein Kinase C Inhibition.

Mast cells play an effector role in innate immunity, allergy, and inflammation. Antigen-mediated activation of mast cells initiates signaling events leading to Ca2+ response and the release of inflammatory and allergic mediators from granules. Diseases associated with deregulated mast cell functions are hard to treat and there is an increasing demand for new therapeutic strategies. Miltefosine (hexadecylphosphocholine) is a new candidate for treatment of mast cell-driven diseases as it inhibits activation of mast cells. It has been proposed that miltefosine acts as a lipid raft modulator through its interference with the structural organization of surface receptors in the cell membrane. However, molecular mechanisms of its action are not fully understood. Here, we report that in antigen-activated bone marrow-derived mast cells (BMMCs), miltefosine inhibits degranulation, reorganization of microtubules, as well as antigen-induced chemotaxis. While aggregation and tyrosine phosphorylation of IgE receptors were suppressed in activated cells pre-treated with miltefosine, overall tyrosine phosphorylation levels of Lyn and Syk kinases, and Ca2+ influx were not inhibited. In contrast, lipid raft disruptor methyl-β-cyclodextrin attenuated the Ca2+ influx. Tagged-miltefosine rapidly localized into the cell interior, and live-cell imaging of BMMCs with labeled intracellular granules disclosed that miltefosine inhibited movement of some granules. Immunoprecipitation and in vitro kinase assays revealed that miltefosine inhibited Ca2+- and diacylglycerol-regulated conventional protein kinase C (cPKC) isoforms that are important for mast cell degranulation. Inhibition of cPKCs by specific inhibitor Ly333531 affected activation of BMMCs in the same way as miltefosine. Collectively, our data suggest that miltefosine modulates mast cells both at the plasma membrane and in the cytosol by inhibition of cPKCs. This alters intracellular signaling pathway(s) directed to microtubules, degranulation, and migration.

VitaminA andD in allergy: from experimental animal models and cellular studies to human disease.

IntroductionVitamins A and D are able to modulate innate and adaptive immune responses and may therefore influence the development and the course of allergic diseases.Materials and methodsThis article reviews the current evidence for the experimental effects of vitamins A and D in vivo in animal models and on immune cells in vitro, and discusses their translational implication. A systematic literature search over the last 10 years was performed using MEDLINE and PubMed databases.ResultsDeficiencies of vitamin A or vitamin D in mouse models of allergic asthma seem to exacerbate allergic symptoms along with enhanced lung inflammation and Th2 cytokine production. In contrast, supplementation regimes especially with vitamin D were able to attenuate symptoms in therapeutic mouse models. The active metabolites retinoic acid (RA) and 1,25-dihydroxyvitamin D3 (VD3) induced tolerogenic dendritic cells (DCs) and up-regulated T‑regulatory cells in the allergic sensitization phase, which likely contributes to tolerance induction. Additionally, RA and VD3 maintained the stability of eosinophils and mast cells in the effector phase, thereby reducing allergic mediator release. Thus, both active vitamin metabolites RA and VD3 are able to influence allergic immune responses at several immunological sites.ConclusionAnimal studies predict that vitamin A and D may also be attractive players in the control of allergy in humans. Whether these experimental observations can be translated to the human situation remains open, as results from clinical trials are controversial.

Anti-inflammatory effect of wogonin on allergic responses in ovalbumin-induced allergic rhinitis in the mouse.

BackgroundWogonin is commonly used for the treatment of allergic diseases. However, neither its precise effect in preventing allergic rhinitis (AR) nor its mechanism of action are known.ObjectivesIn this study, the effect of wogonin on allergic responses in ovalbumin (OVA) induced AR was investigated in mice.MethodsBALB/c mice were sensitized with intraperitoneal (i.p.) OVA and then challenged intranasally with OVA. Wogonin (10 and 30 mg/kg) was given to the treatment groups, and the effect of wogonin on the release of allergic inflammatory mediators, specifically OVA-specific immunoglobulin E (IgE) and inflammatory cytokines, was explored. Eosinophil infiltration and the levels of interleukin (IL) 5 and IL-13 were measured by immunohistochemistry.ResultsIn mice with AR, wogonin decreased OVA-specific IgE levels in serum, and the levels of the cytokines IL-4, IL-5, IL-13, eotaxin, and RANTES in nasal lavage fluid. Serum levels of IL-4, IL-5, and IL-13 were lower in both groups of wogonin-pretreated mice than in the OVA group. A reduction in eosinophil infiltration of the nasal mucosa and inhibition of the expression of IL-5 and IL-13 were also noted in the treated groups.ConclusionWogonin induced antiallergic effects in a murine model of AR by decreasing the infiltration of eosinophils and levels of T-helper type 2 cytokines. Thus, wogonin merits consideration as a therapeutic agent for treating AR.

Fresh water, marine and terrestrial cyanobacteria display distinct allergen characteristics

During the last decades, global cyanobacteria biomass increased due to climate change as well as industrial usage for production of biofuels and food supplements. Thus, there is a need for thorough characterization of their potential health risks, including allergenicity. We therefore aimed to identify and characterize similarities in allergenic potential of cyanobacteria originating from the major ecological environments. Different cyanobacterial taxa were tested for immunoreactivity with IgE from allergic donors and non-allergic controls using immunoblot and ELISA. Moreover, mediator release from human FcεR1-transfected rat basophilic leukemia (RBL) cells was measured, allowing in situ examination of the allergenic reaction. Phycocyanin content and IgE-binding potential were determined and inhibition assays performed to evaluate similarities in IgE-binding epitopes. Mass spectrometry analysis identified IgE-reactive bands ranging between 10 and 160kDa as phycobiliprotein compounds. Levels of cyanobacterial antigen-specific IgE in plasma of allergic donors and mediator release from sensitized RBL cells were significantly higher compared to non-allergic controls (p<0.01). Inhibition studies indicated cross-reactivity between IgE-binding proteins from fresh water cyanobacteria and phycocyanin standard. We further addressed IgE-binding characteristics of marine water and soil-originated cyanobacteria. Altogether, our data suggest that the intensive use and the strong increase in cyanobacterial abundance due to climate change call for increasing awareness and further monitoring of their potential health hazards.

IL-6 induces production of VEGF and MCP-1 from human skin mast cells.

Abstract Mast cells are the cell type responsible for IgE-mediated allergic reactions, and are involved in innate immunity against bacteria and pathogens. Interestingly, recent research has implicated mast cells in traditionally non-allergic diseases such as cancer. It has been hypothesized that in these non-allergic diseases mast cells may be activated by stimuli other than antigen, such as pro-inflammatory cytokines. Interleukin-6 (IL-6) is a pleiotropic cytokine that has been implicated in several diseases in which mast cells are also believed to contribute, suggesting that IL-6 could be the link that connects mast cells to non-allergic disease. However, the surface expression of IL-6 receptors, and the effect of IL-6 on human tissue-derived mast cells remained to be determined. Here, we show that human skin mast cells express functional membrane-bound IL-6 receptors, and address the role of IL-6 on the release of allergic and inflammatory mediators. Stimulation of skin mast cells with IL-6 resulted in a dose-dependent increase in Signal Transducer and Activator of Transcription 3 (STAT-3) phosphorylation, and increased expression of Suppressor of Cytokine Signaling 3 (SOCS3) mRNA. IL-6 had no effect on degranulation, but enhanced PGD2 biosynthesis and IL-8 production following FcɛRI crosslinking. In addition, treatment with IL-6 alone was sufficient to induce the production of monocyte chemoattractant protein (MCP-1) and vascular endothelial growth factor (VEGF). Overall, these findings clarify the effect of IL-6 on the allergic response from human tissue-derived mast cells, and reveal a potential role for IL-6 in mast cell-mediated angiogenesis.

Is Andrographis paniculata extract and andrographolide anaphylactic?

Andrographis paniculata, "King of bitters" is a popularly known medicinal plant extensively used in many parts of the world for treatment of various diseases. Since recent past, anaphylactic/allergic type adverse events were reported upon A. paniculata usage, the study aimed to evaluate the anaphylactic and anaphylactoid potential of A. paniculata extract and andrographolide (a major phytoactive of A. paniculata). The anaphylactic potential was evaluated using active systemic anaphylaxis (ASA) assay in guinea pigs. Further, the release of allergic mediators was measured in immunoglobulin E (IgE) sensitized and non-IgE sensitized Rat Basophilic Leukemia (RBL-2H3) cell lines in-vitro. A. paniculata extract or andrographolide sensitized guinea pigs following the challenge antigen administration orally and intravenously did not demonstrate any clinical signs of anaphylaxis. IgE sensitized and non- IgE sensitized RBL-2H3 cells treated with A. paniculata extract did not induce release of allergic mediators. Whereas IgE sensitized and non- IgE sensitized RBL-2H3 cells treated with andrographolide demonstrated mild to moderate release of allergic mediators. A. paniculata extract has no anaphylactic and anaphylactoid potential in in-vivo and in-vitro studies. Whereas, andrographolide effects on allergic mediators in in-vitro studies needs to be scrutinized if they are of biologically important.

Kinesin-1 controls mast cell degranulation and anaphylaxis through PI3K-dependent recruitment to the granular Slp3/Rab27b complex.

Cross-linking of mast cell (MC) IgE receptors (FcεRI) triggers degranulation of secretory granules (SGs) and the release of many allergic and inflammatory mediators. Although degranulation depends crucially on microtubule dynamics, the molecular machinery that couples SGs to microtubule-dependent transport is poorly understood. In this study, we demonstrate that mice lacking Kif5b (the heavy chain of kinesin-1) in hematopoietic cells are less sensitive to IgE-mediated, passive, systemic anaphylaxis. After IgE-induced stimulation, bone marrow-derived MCs from Kif5b knockout mice exhibited a marked reduction in SG translocation toward the secretion site. In contrast, a lack of Kif5b did not affect cytokine secretion, early FcεRI-initiated signaling pathways, or microtubule reorganization upon FcεRI stimulation. We identified Slp3 as the critical effector linking kinesin-1 to Rab27b-associated SGs. Kinesin-1 recruitment to the Slp3/Rab27b effector complex was independent of microtubule reorganization but occurred only upon stimulation requiring phosphatidylinositol 3-kinase (PI3K) activity. Our findings demonstrate that PI3K-dependent formation of a kinesin-1/Slp3/Rab27b complex is critical for the microtubule-dependent movement of SGs required for MC degranulation.

Constituents from oak bark (Quercus robur L.) inhibit degranulation and allergic mediator release from basophils and mast cells in vitro

Ethnopharmacological relevanceOak bark has been used since ancient times in Europaen ethnomedicine because of its adstringent, antimicrobial and hemostatic features, e.g. as a remedy for the treatment of wounds and skin diseases. PurposeOak bark tannins are considered as bioactive natural products, interacting with surface proteins of mucous membranes and might be beneficial for the treatment of allergic diseases. This study investigated the effect of an oak bark decoction (OBD) and isolated tannin fractions on the degranulation capacity and cytokine/chemokine release from rat basophilic cells and human mast cells in vitro, which are essential for the initiation of early- and late-phase allergic reactions. Methods and methodsBy chromatographic separation on Sephadex® LH-20 high- and low-molecular weight tannins were separated from OBD and the tannin composition analyzed by HPLC(DAD)-MSn. Then, the OBD and its fractions were tested in degranulation (β-hexosaminidase activity) of allergen-specific-activated basophilic cells in a photometric assay. ResultsThe OBD and the high-molecular tannin fraction showed a dose-dependent inhibition of cell degranulation. Furthermore, the OBD and particularly its high molecular weight tannin fraction exhibited an inhibitory activity on the IL-8-, IL-6- and TNF-α-secretion from stimulated human mast cells, detected and quantified by ELISA. ConclusionThe OBD and its high-molecular weight tannins revealed an impact on allergic mediator release of basophilic cells and human mast cells and thereby provide a rationale for the topical treatment with OBD preparations.

Resveratrol preferentially inhibits IgE-dependent PGD2 biosynthesis but enhances TNF production from human skin mast cells

BackgroundResveratrol, a natural polyphenol found in the skin of red grapes, is reported to have anti-inflammatory properties including protective effects against aging. Consequently, Resveratrol is a common nutritional supplement and additive in non-prescription lotions and creams marketed as anti-aging products. Studies in mice and with mouse bone marrow-derived mast cells (BMMCs) have indicated anti-allergic effects of Resveratrol. However, the effects of Resveratrol on human primary mast cells have not been reported. MethodsHuman mast cells were isolated and purified from normal skin tissue of different donors. The effect of Resveratrol on IgE-dependent release of allergic inflammatory mediators was determined using various immunoassays, Western blotting, and quantitative real-time PCR. ResultsResveratrol at low concentrations (≤10μM) inhibited PGD2 biosynthesis but not degranulation. Accordingly, COX-2 expression was inhibited but phosphorylation of Syk, Akt, p38, and p42/44 (ERKs) remained intact. Surprisingly, TNF production was significantly enhanced with Resveratrol. At a high concentration (100μM), Resveratrol significantly inhibited all parameters analyzed except Syk phosphorylation. ConclusionsHere, we show that Resveratrol at low concentrations exerts its anti-inflammatory properties by preferentially targeting the arachidonic acid pathway. We also demonstrate a previously unrecognized pro-inflammatory effect of Resveratrol — the enhancement of TNF production from human mature mast cells following IgE-dependent activation. General significanceThese findings suggest that Resveratrol as a therapeutic agent could inhibit PGD2-mediated inflammation but would be ineffective against histamine-mediated allergic reactions. However, Resveratrol could potentially exacerbate or promote allergic inflammation by enhancing IgE-dependent TNF production from mast cells in human skin.

Anti-inflammatory effect of curcumin on mast cell-mediated allergic responses in ovalbumin-induced allergic rhinitis mouse

Curcumin has commonly been used for the treatment of various allergic diseases. However, its precise anti-allergic rhinitis effect and mechanism remain unknown. In the present study, the effect of curcumin on allergic responses in ovalbumin (OVA)-induced allergic rhinitis mouse was investigated. We explored the effect of curcumin on the release of allergic inflammatory mediators, such as histamine, OVA-specific IgE, and inflammatory cytokines. Also, we found that curcumin improved rhinitis symptoms, inhibited the histopathological changes of nasal mucosa, and decreased the serum levels of histamine, OVA-specific IgE and TNF-α in OVA-induced allergic rhinitis mice. In addition, curcumin suppressed the production of inflammatory cytokines, such as TNF-α, IL-1β, IL-6 and IL-8. Moreover, curcumin significantly inhibited PMA-induced p-ERK, p-p38, p-JNK, p-Iκ-Bα and NF-κB. These findings suggest that curcumin has an anti-allergic effect through modulating mast cell-mediated allergic responses in allergic rhinitis, at least partly by inhibiting MAPK/NF-κB pathway.