Inhibitory effects of whisky congeners on IgE-mediated degranulation in rat basophilic leukemia RBL-2H3 cells and passive cutaneous anaphylaxis reaction in mice

The reason and mechanism of propylene glycol alginate sodium sulfate (PSS) mediated allergic side effect

Propylene glycol alginate sodium sulfate (PSS) is a heparinoid polysaccharide drug used in clinic for >30 years in China. But its allergy events happened from time to time and should not be ignored. Here, ammonium salt in PSS (PSS-NH₄⁺), PSS fractions with high Mw (PSS-H-Mw) and low mannuronic acid (M) to guluronic acid (G) ratio (PSS-L-M/G) were found to induce allergic response by the structure-activity and impurity-activity relationships in vitro. Furthermore, we confirmed the reason and elucidated the mechanism accounted for allergic side effect of PSS in vivo. It was found that high IgE levels in PSS-NH₄⁺ and PSS-H-Mw groups upregulate the cascade expression of Lyn-Syk-Akt or Erk and second messenger Ca²⁺, which accelerated mast cells (MCs) degranulation to release histamine, LTB4, TPS, and finally induced lung tissue injury. PSS-L-M/G caused mild allergic symptom because it only enhanced the expression of p-Lyn and histamine release. In brief, PSS-NH₄⁺ and PSS-H-Mw were main reasons to result in allergic response. Our results suggested that it is very necessary to control the range of Mw and the content of impurities (< 1 % ammonium salt) of PSS to guarantee its safety and effectiveness in clinical treatment.

Total Asymmetric Synthesis and Stereochemical Confirmation of (+)- and (-)-Lyoniresinol and Its Deuterated Analogues

Lyoniresinol and its derivatives are lignans which have been isolated from a plethora of plant species. In addition to exhibiting a range of interesting biological activities including anticancer, anti-inflammatory, antimicrobial, and others, these compounds have also been discovered in wines and spirits and shown to have gustatory effects in these alcoholic matrices. (+)-Lyoniresinol 1 is reported to impart a strong bitter taste while its enantiomer (-)-lyoniresnol 2 is tasteless. The first total asymmetric synthesis of both natural enantiomers (+)-1 and (-)-2 and their deuterated analogues (D₄)-(+)-3 and (D₄)-(-)-4 has been achieved, confirming the structure and stereochemistry of the natural products. The synthesized compounds can be utilized as internal standards in stable isotope dilution analysis for improving and optimizing the existing lyoniresinol quantitation methods in the future.

Mast Cells Localize in Hypoxic Zones of Tumors and Secrete CCL-2 under Hypoxia through Activation of L-Type Calcium Channels

Hypoxia is a condition that together with low pH, high amounts of reactive oxygen species (ROS), and increased adenosine levels characterize tumor microenvironment. Mast cells (MCs) are part of tumor microenvironment, but the effect of hypoxia on the production of MC-derived cytokines has not been fully described. Using the hypoxia marker pimonidazole in vivo, we found that MCs were largely located in the low-oxygen areas within B16-F1 mice melanoma tumors. In vitro, hypoxia promoted ROS production, a ROS-dependent increase of intracellular calcium, and the production of MCP 1 (CCL-2) in murine bone marrow-derived MCs. Hypoxia-induced CCL-2 production was sensitive to the antioxidant trolox and to nifedipine, a blocker of L-type voltage-dependent Ca²⁺ channels (LVDCCs). Simultaneously with CCL-2 production, hypoxia caused the ROS-dependent glutathionylation and membrane translocation of the α1c subunit of Cav1.2 LVDCCs. Relationship between ROS production, calcium rise, and CCL-2 synthesis was also observed when cells were treated with H₂O₂ In vivo, high CCL-2 production was detected on hypoxic zones of melanoma tumors (where tryptase-positive MCs were also found). Pimonidazole and CCL-2 positive staining diminished when B16-F1 cell-inoculated animals were treated with trolox, nifedipine, or the adenosine receptor 2A antagonist KW6002. Our results show that MCs are located preferentially in hypoxic zones of melanoma tumors, hypoxia-induced CCL-2 production in MCs requires calcium rise mediated by glutathionylation and membrane translocation of LVDCCs, and this mechanism of CCL-2 synthesis seems to operate in other cells inside melanoma tumors, with the participation of the adenosine receptor 2A.

Dammarane-type triterpenoids from the stem of Ziziphus glaziovii Warm. (Rhamnaceae)

Seven undescribed dammarane-type triterpenoids, together with ten known compounds, were isolated from the stems of Ziziphus glaziovii Warm (= Sarcomphalus glaziovii (Warm.) Hauenschild). The structures were fully assigned by means of uni- and bidimensional NMR and HR-ESI-MS experiments. Extract, fractions and also isolated compounds were evaluated for their antibacterial (against Bacillus subtilis and Aliivibrio fischeri), cytotoxic (against PC-3 and HT-29 human cancer cell lines), anthelmintic (against Caenorhabditis elegans) and antifungal (against Septoria triciti, Botrytis cinerea and Phytopthoria infestans) activities. The methanolic crude extract exhibited substantial antibacterial and cytotoxic activity. The known triterpenes epigouanic acid and alphitolic acid were the most active compounds against B. subtilis, with IC50 of 12 and 22 μM, respectively. The isolated compounds presented up to a concentration of 10 μM none or only weak effects in the cytotoxicity assays. No anthelminthic and antifungal activities were observed.

Chemoinformatic Analysis of Selected Cacalolides from Psacalium decompositum (A. Gray) H. Rob. & Brettell and Psacalium peltatum (Kunth) Cass. and Their Effects on FcεRI-Dependent Degranulation in Mast Cells

Cacalolides are a kind of sesquiterpenoids natural compounds synthesized by Psacalium decompositum (A. Gray) H. Rob. & Brettell or Psacalium peltatum (Kunth) Cass. Antioxidant and hypoglycemic effects have been found for cacalolides such as cacalol, cacalone or maturine, however, their effects on inflammatory processes are still largely unclear. The main aim of this study was to investigate the biological activities of secondary metabolites from P. decompositum and P. peltatum through two approaches: (1) chemoinformatic and toxicoinformatic analysis based on ethnopharmacologic background; and (2) the evaluation of their potential anti-inflammatory/anti-allergic effects in bone marrow-derived mast cells by IgE/antigen complexes. The bioinformatics properties of the compounds: cacalol; cacalone; cacalol acetate and maturin acetate were evaluated through Osiris DataWarrior software and Molinspiration and PROTOX server. In vitro studies were performed to test the ability of these four compounds to inhibit antigen-dependent degranulation and intracellular calcium mobilization, as well as the production of reactive oxygen species in bone marrow-derived mast cells. Our findings showed that cacalol displayed better bioinformatics properties, also exhibited a potent inhibitory activity on IgE/antigen-dependent degranulation and significantly reduced the intracellular calcium mobilization on mast cells. These data suggested that cacalol could reduce the negative effects of the mast cell-dependent inflammatory process.

Ergosterol and its derivatives from Grifola frondosa inhibit antigen-induced degranulation of RBL-2H3 cells by suppressing the aggregation of high affinity IgE receptors

Grifola frondosa is an edible mushroom consumed as a health food and/or traditional medicine in Asia. However, the anti-allergic effects of G. frondosa are not yet understood. In this study, we demonstrated the effects of G. frondosa extract (GFE) on IgE-mediated allergic responses, using antigen-stimulated RBL-2H3 cells. Three active compounds: ergosterol, 6β-methoxyergosta-7,22-dien-3β,5α-diol (MEDD), and 6-oxoergosta-7,22-dien-3β-ol (6-OXO) were isolated from GFE and shown to inhibit the antigen-induced release of β-hexosaminidase and histamine. Among the three active components, we focused on ergosterol because of its high content in GFE. Ergosterol inhibited the aggregation of high-affinity IgE receptor (FcεRI), which is the first step in the activation of mast cells and antigen-induced tyrosine phosphorylation. Furthermore, ergosterol suppressed antigen-increased IL-4 and TNF-α mRNA. Taken together, our findings suggest that G. frondosa, including ergosterol and its derivatives as active components, has the potential to be a novel functional food that prevents type I allergies.

Biological and epidemiological evidence of anti-allergic effects of traditional Japanese food ume (Prunus mume)

Japanese apricot (Prunus mume; ume) is a traditional food in Japan that has been shown to have various beneficial health effects. There is some evidence to suggest that ume is also effective against allergic disease. Here, we conducted a cross-sectional epidemiological pilot study to examine the association between ume intake frequency and allergic symptoms including rhinitis in 563 adults (288 men and 275 women) who resided in Wakayama, Japan. After adjusting for age, present illness and medication, women with high ume intake had significantly lower odds ratio (OR) for the presence of symptoms of allergy [OR: 0.49 with 95% confidence interval (CI): 0.25-0.97]. Therefore, we investigated the anti-allergic effect of ume on passive cutaneous anaphylaxis (PCA) reaction in immunoglobulin E (IgE)-sensitized mice. The animal study demonstrated that oral administration of ume extract attenuated the PCA reaction and mast cell degranulation. Furthermore, RBL-2H3 mast cells were used to identify anti-allergic ume compounds. The following ume compounds inhibited IgE-mediated mast cell degranulation: vanillin, syringic acid, protocatechuic aldehyde, lyoniresinol and p-coumaric acid. These results suggested that ume has the potential to inhibit mast cell degranulation and may be associated with reduced risk of allergic symptoms in women.

Jacareubin inhibits FcεRI-induced extracellular calcium entry and production of reactive oxygen species required for anaphylactic degranulation of mast cells

Mast cells (MCs) are important effectors in allergic reactions since they produce a number of pre-formed and de novo synthesized pro-inflammatory compounds in response to the high affinity IgE receptor (FcεRI) crosslinking. IgE/Antigen-dependent degranulation and cytokine synthesis in MCs have been recognized as relevant pharmacological targets for the control of deleterious inflammatory reactions. Despite the relevance of allergic diseases worldwide, efficient pharmacological control of mast cell degranulation has been elusive. In this work, the xanthone jacareubin was isolated from the heartwood of the tropical tree Callophyllum brasilense, and its tridimensional structure was determined for the first time by X-ray diffraction. Also, its effects on the main activation parameters of bone marrow-derived mast cells (BMMCs) were evaluated. Jacareubin inhibited IgE/Ag-induced degranulation in a dose-response manner with an IC₅₀ = 46 nM. It also blocked extracellular calcium influx triggered by IgE/Ag complexes and by the SERCA ATPase inhibitor thapsigargin (Thap). Inhibition of calcium entry correlated with a blockage on the reactive oxygen species (ROS) accumulation. Antioxidant capacity of jacareubin was higher than the showed by α-tocopherol and caffeic acid, but similar to trolox. Jacareubin shown inhibitory actions on xanthine oxidase, but not on NADPH oxidase (NOX) activities. In vivo, jacareubin inhibited passive anaphylactic reactions and TPA-induced edema in mice. Our data demonstrate that jacareubin is a potent natural compound able to inhibit anaphylactic degranualtion in mast cells by blunting FcεRI-induced calcium flux needed for secretion of granule content, and suggest that xanthones could be efficient anti-oxidant, antiallergic, and antiinflammatory molecules.

Mexican Propolis: A Source of Antioxidants and Anti-Inflammatory Compounds, and Isolation of a Novel Chalcone and ε-Caprolactone Derivative

The propolis produced by bees are used in alternative medicine for treating inflammation, and infections, presumably due to its antioxidant properties. In this context, five propolis from México were investigated to determine their inhibitory lipid peroxidation properties. The ethyl acetate extract from a red propolis from Chiapas State (4-EAEP) was the most potent (IC₅₀ = 1.42 ± 0.07 μg/mL) in the TBARS assay, and selected for further studies. This extract afforded two new compounds, epoxypinocembrin chalcone (6), and an ε-caprolactone derivative (10), as well as pinostrobin (1), izalpinin (2), cinnamic acid (3), pinocembrin (4), kaempherol (5), 3,3-dimethylallyl caffeate in mixture with isopent-3-enyl caffeate (7a + 7b), 3,4-dimethoxycinnamic acid (8), rhamnetin (9) and caffeic acid (11). The HPLC profile, anti-mycobacterial, and antioxidant properties of this extract was also determined. Most of the isolated compounds were also tested by inhibition of reactive oxygen species (ROS) in challenged mouse bone marrow-derived mast cells (BMMCs), and DPPH. Their anti-inflammatory activity was evaluated by TPA, and MPO (myeloperoxidase) activity by ear edema test in mice. The most potent compounds were 7a + 7b in the TBARS assay (IC₅₀ = 0.49 ± 0.06 μM), and 2 which restored the ROS baseline (3.5 μM). Our results indicate that 4-EAEP has anti-oxidant, and anti-inflammatory properties due to its active compounds, suggesting it has anti-allergy and anti-asthma potential.

Suppressive effect of ethanol extract from mango (Mangifera indica L.) peel on IgE production in vitro and in vivo

Immunoglobulin E (IgE) is involved in the onset of allergic reaction, and the suppression of IgE production leads to alleviation of allergic symptoms. We found that mango peel ethanol extract (MPE) significantly suppresses IgE production by human myeloma cell line U266 cells, suggesting that MPE has an anti-allergic effect by inhibiting the production of IgE. Although mangiferin is contained in mango, which suppresses IgE production by U266 cells, it was not contained in MPE. We investigated the suppressive effect of MPE in 2,4-dinitrofluorobenzene (DNFB)-induced allergic contact dermatitis model mice. The elevation of serum IgE level was significantly suppressed by oral administration of MPE. Intake of MPE also suppressed the expression level of IL-4 in the DNFB-challenged ears, suggesting that MPE suppresses the IL-4-mediated maturation into IgE-producing cells. Our findings indicate that MPE has a potential to alleviate the increase in serum IgE level that is feature of type I allergy.

Anti-allergic and anti-inflammatory effects of aqueous extract of Pogostemon cablin

Allergic disease is caused by exposure to normally innocuous substances that activate mast cells. Mast cell-mediated allergic inflammation is closely related to a number of allergic disorders, such as anaphylaxis, allergic rhinitis, asthma and atopic dermatitis. The discovery of drugs for treating allergic disease is an interesting subject and important to human health. The aim of the present study was to investigate the anti‑allergic and anti-inflammatory effects of the aqueous extract of Pogostemon cablin (Blanco) Benth (AEPC) (a member of the Labiatae family) using mast cells, and also to determine its possible mechanisms of action. An intraperitoneal injection of compound 48/80 or a serial injection of immunoglobulin E and antigen was used to induce anaphylaxis in mice. We found that AEPC inhibited compound 48/80‑induced systemic and immunoglobulin E-mediated cutaneous anaphylaxis in a dose-dependent manner. The release of histamine from mast cells was reduced by AEPC, and this suppressive effect was associated with the regulation of calcium influx. In addition, AEPC attenuated the phorbol 12-myristate 13-acetate plus calcium ionophore A23187 (PMACI)-stimulated expression of pro-inflammatory cytokines in mast cells. The inhibitory effects of AEPC on pro-inflammatory cytokines were dependent on the activation of nuclear factor (NF)-κB and p38 mitogen-activated protein kinase (MAPK). AEPC blocked the PMACI-induced translocation of NF-κB into the nucleus by hindering the degradation of IκBα and the phosphorylation of p38 MAPK. Our results thus indicate that AEPC inhibits mast cell‑mediated allergic inflammation by suppressing mast cell degranulation and the expression of pro-inflammatory cytokines caused by reduced intracellular calcium levels and the activation of NF-κB and p38 MAPK.

Inhibitory effect of 1,2,4,5-tetramethoxybenzene on mast cell-mediated allergic inflammation through suppression of IκB kinase complex

As the importance of allergic disorders such as atopic dermatitis and allergic asthma, research on potential drug candidates becomes more necessary. Mast cells play an important role as initiators of allergic responses through the release of histamine; therefore, they should be the target of pharmaceutical development for the management of allergic inflammation. In our previous study, anti-allergic effect of extracts of Amomum xanthioides was demonstrated. To further investigate improved candidates, 1,2,4,5-tetramethoxybenzene (TMB) was isolated from methanol extracts of A. xanthioides. TMB dose-dependently attenuated the degranulation of mast cells without cytotoxicity by inhibiting calcium influx. TMB decreased the expression of pro-inflammatory cytokines such as tumor necrosis factor-α and interleukin (IL)-4 at both the transcriptional and translational levels. Increased expression of these cytokines was caused by translocation of nuclear factor-κB into the nucleus, and it was hindered by suppressing activation of IκB kinase complex. To confirm the effect of TMB in vivo, the ovalbumin (OVA)-induced active systemic anaphylaxis (ASA) and IgE-mediated passive cutaneous anaphylaxis (PCA) models were used. In the ASA model, hypothermia was decreased by oral administration of TMB, which attenuated serum histamine, OVA-specific IgE, and IL-4 levels. Increased pigmentation of Evans blue was reduced by TMB in a dose-dependent manner in the PCA model. Our results suggest that TMB is a possible therapeutic candidate for allergic inflammatory diseases that acts through the inhibition of mast cell degranulation and expression of pro-inflammatory cytokines.

SG-HQ2 inhibits mast cell-mediated allergic inflammation through suppression of histamine release and pro-inflammatory cytokines

In this study, we investigated the effect of 3,4,5-trihydroxy-N-(8-hydroxyquinolin-2-yl)benzamide) (SG-HQ2), a synthetic analogue of gallic acid (3,4,5-trihydroxybenzoic acid), on the mast cell-mediated allergic inflammation and the possible mechanism of action. Mast cells play major roles in immunoglobulin E-mediated allergic responses by the release of histamine, lipid-derived mediators, and pro-inflammatory cytokines. We previously reported the potential effects of gallic acid using allergic inflammation models. For incremental research, we synthesized the SG-HQ2 by the modification of functional groups from gallic acid. SG-HQ2 attenuated histamine release by the reduction of intracellular calcium in human mast cells and primary peritoneal mast cells. The inhibitory efficacy of SG-HQ2 was similar with gallic acid. Enhanced expression of pro-inflammatory cytokines such as tumor necrosis factor-α, interleukin-1β, interleukin-4, and interleukin-6 in activated mast cells was significantly diminished by SG-HQ2 100 times lower concentration of gallic acid. This inhibitory effect was mediated by the reduction of nuclear factor-κB. In animal models, SG-HQ2 inhibited compound 48/80-induced serum histamine release and immunoglobulin E-mediated local allergic reaction, passive cutaneous anaphylaxis. Our results indicate that SG-HQ2, an analogue of gallic acid, might be a possible therapeutic candidate for mast cell-mediated allergic inflammatory diseases through suppression of histamine release and pro-inflammatory cytokines.

Inhibitory effects of Diospyros kaki in a model of allergic inflammation: role of cAMP, calcium and nuclear factor-κB

Diospyros kaki (D. kaki) has been cultivated throughout Eastern Asia for hundreds of years. D. kaki contains various biological active compounds, such as amino acids, carotenoids, flavonoids, tannins, catechins and vitamin A. Previous studies have shown that D. kaki has beneficial effects on homeostasis, constipation, hypertension, atherosclerosis and allergic dermatitis and is a good source of antioxidants, polyphenols and dietary fiber. However, the anti-allergic and anti-inflammatory effects of D. kaki have not yet been elucidated. This study aimed to investigate the protective effects of the aqueous extract of Diospyros kaki (AEDK) on mast cell-mediated allergic inflammation and to determine its possible mechanisms of action by using in vitro and in vivo mast cell-based models. The cAMP and intracellular calcium levels were measured to clarify the mechanisms by which AEDK inhibits the release of histamine from mast cells. AEDK inhibited the release of histamine and β-hexosaminidase from mast cells by modulating cAMP and intracellular calcium levels. We also measured the expression of pro-inflammatory cytokines, such as tumor necrosis factor (TNF)-α and interleukin (IL)-1β. AEDK decreased gene expression and the secretion of the pro-inflammatory cytokines, TNF-α and IL-1β by inhibiting nuclear factor-κB. In addition, AEDK inhibited systemic and cutaneous allergic reaction. The inhibitory effects of AEDK on allergic reaction and the release of histamine were found to be similar to those of disodium cromoglycate, a known anti-allergic drug. To isolate the active component of AEDK, activity-guided fractionation was performed, based on the inhibitory effects on systemic anaphylaxis. Catechin was identified as an active compound. The present findings provide evidence that AEDK inhibits allergic inflammation and suggest the therapeutic application of AEDK in allergic inflammatory disorders.

Polydatin (PD) inhibits IgE-mediated passive cutaneous anaphylaxis in mice by stabilizing mast cells through modulating Ca²⁺ mobilization

Mast cells play a key role in the pathogenesis of asthma and are a promising target for therapeutic intervention in asthma. This study investigated the effects of polydatin (PD), a resveratrol glucoside, on mast cell degranulation upon cross-linking of the high-affinity IgE receptors (FcεRI), as well as the anti-allergic activity of PD in vivo. Herein, we demonstrated that PD treatment for 30 min suppressed FcεRI-mediated mast cell degranulation in a dose-dependent manner. Concomitantly, PD significantly decreased FcεRI-mediated Ca²⁺ increase in mast cells. The suppressive effects of PD on FcεRI-mediated Ca²⁺ increase were largely inhibited by using LaCl₃ to block the Ca²⁺ release-activated Ca²⁺ channels (CRACs). Furthermore, PD significantly inhibited Ca²⁺ entry through CRACs evoked by thapsigargin (TG). Knocking down protein expression of Orai1, the pore-forming subunit of CRACs, significantly decreased PD suppression of FcεRI-induced intracellular Ca²⁺ influx and mast cell degranulation. In a mouse model of mast cell-dependent passive cutaneous anaphylaxis (PCA), in vivo PD administration suppressed mast cell degranulation and inhibited anaphylaxis. Taken together, our data indicate that PD stabilizes mast cells by suppressing FcεRI-induced Ca²⁺ mobilization mainly through inhibiting Ca²⁺ entry via CRACs, thus exerting a protective effect against PCA.

Inhibitory effect of eriodictyol on IgE/Ag-induced type I hypersensitivity

Mast cells are the principal effector cells involved in the allergic response, through the release of histamine. We investigated the effect of eriodictyol, derived from the painted maple and yerba santa, on mast cell degranulation and on an allergic response in an animal model. We also investigated its effect on the expression of the ceramide kinase (CERK) involved in calcium-dependent degranulation, and on ceramide activation by multiple cytokines. Eriodictyol suppressed the release of beta-hexosaminidase, a marker of degranulation, and the expression of interleukin (IL)-4 mRNA. It inhibited the expression of CERK mRNA, reduced the ceramide concentration in antigen-stimulated mast cells, and suppressed the passive cutaneous anaphylaxis (PCA) reaction in mice in a dose-dependent manner. These results suggest that eriodictyol can inhibit mast cell degranulation through inhibition of ceramide kinase, and that it might potentially serve as an anti-allergic agent.

Lipopolysaccharide enhances FcεRI-mediated mast cell degranulation by increasing Ca2+ entry through store-operated Ca2+ channels: implications for lipopolysaccharide exacerbating allergic asthma

Lipopolysaccharide (LPS) can exacerbate asthma; however, the mechanisms are not fully understood. This study investigated the effect of LPS on antigen-stimulated mast cell degranulation and the underlying mechanisms. We found that LPS enhanced degranulation in RBL-2H3 cells and mouse peritoneal mast cells upon FcεRI activation, in a dose- and time-dependent manner. Parallel to the alteration of degranulation, LPS increased FcεRI-activated Ca(2+) mobilization, as well as Ca(2+) entry through store-operated calcium channels (SOCs) evoked by thapsigargin. Blocking Ca(2+) entry through SOCs completely abolished LPS enhancement of mast cell degranulation. Consistent with functional alteration of SOCs, LPS increased mRNA and protein levels of Orai1 and STIM1, two major subunits of SOCs, in a time-dependent manner. In addition, LPS increased the mRNA level of Toll-like receptor 4 (TLR4) in a time-dependent manner. Blocking TLR4 with Cli-095 inhibited LPS, increasing transcription and expression of SOC subunits. Concomitantly, the effect of LPS enhancement of Ca(2+) mobilization and mast cell degranulation was largely reduced by Cli-095. Administration of LPS (1 μg) in vivo aggravated airway hyperreactivity and inflammatory reactions in allergic asthmatic mice. Histamine levels in serum and bronchoalveolar lavage fluid were increased by LPS treatment. In addition, Ca(2+) mobilization was enhanced in peritoneal mast cells isolated from LPS-treated asthmatic mice. Taken together, these results imply that LPS enhances mast cell degranulation, which potentially contributes to LPS exacerbating allergic asthma. Lipopolysaccharide increases Ca(2+) entry through SOCs by upregulating transcription and expression of SOC subunits, mainly through interacting with TLR4 in mast cells, resulting in enhancement of mast cell degranulation upon antigen stimulation.