Mast Cell Stabilizing, Antianaphylactic and Bronchodilatory activity of Methanolic extract of Averrhoa carambola Fruit

This work was mainly aimed to study the mast cell stabilizing, anti-anaphylactic and bronchodilatory activities of methanolic extract of Averrhoa carambola (ACME). Mast cell stabilization activity was investigated by Compound 48/80 induced mast cell degranulation in rats and antianaphylactic activity was performed by determining the mortality rate of mice upon exposure to compound 48/80. The bronchodilatory effect of ACME was studied on histamine aerosol-induced bronchospasm using guinea pigs, in which occurrence of preconvulsive dyspnea (PCD) was noted as end point. Treatment with ACME (100, 200 and 400mg/kg) showed significant (p<0.05) protection of rat peritoneal mast cells and significantly (p<0.05) reduced the mortality of mice in a dose dependent manner. ACME significantly (p<0.05) increased the time of preconvulsive dyspnea (PCD) in a dose dependent manner that suggestive of bronchodilating activity. Phytochemical studies observed presence of saponins, tannins, steroids, alkaloids, flavonoids and glycosides. From these finding, we concluded that ACME possesses mast cell stabilizing; anti anaphylactic and bronchodilatory activity which might be used in treatment of asthma.

COMPARATIVE STUDY OF HISTOLOGICAL AND HISTOCHEMICAL PROPERTIES OF PERITONEAL MAST CELLS OF ALBINO RAT USING TWO TYPES OF FIXATIVES

Objectives: To make a comparative study of histological and histochemical properties of peritoneal mast cells in albino rat using neutral buffered formalin and formal alcohol as fixatives. Methods: The stretch preparation from Albino rat peritoneum was made on chemically clean glass slides and immediately placed into the fixatives. Results: With toluidine blue (pH 4.4), the mast cells stained deep purple and similar reaction was obtained with toluidine blue at pH 2. These staining reactions indicate the presence of substantial amount of heparin trisulfate, small amount of heparin monosulfate, and neutral mucopolysaccharide. Conclusion: Heparin trisulfate is an active form of heparin and is the main constituent of the mast cell granules of the albino rat.

P2X7 on mast cells participates in peripheral pain and serves as a potential target for salicylic acid and aspirin analgesia

Background Extracellular ATP signaling through excitatory and calcium-permeable P2X receptor channels is considered as a critical player in pain generation and maintenance. P2X7 has attracted much attention over the past decade because of its prominent role in driving inflammatory processes. The role of P2X7 in mast cells in peripheral pain remains unclear.Methods P2X expression in mouse peritoneal mast cells was detected by RT-PCR. The subtypes of P2X receptors in mouse peritoneal mast cells were determined with a series of blockers by using calcium imaging and electrophysiology. The regulation of inflammatory factors mediated by different P2X subtypes were detected by ELISA and real-time PCR. The role of mast cells and P2X7 receptor in peripheral pain was explored by behavioral assays, pathological analysis and real-time PCR. Several anti-inflammatory small molecules were screened based on P2X7 in mast cells by using calcium imaging, electrophysiology and molecular docking.Results We found that ATP was significantly increased in inflammatory pain. Mouse peritoneal mast cells expressed P2X1, P2X3, P2X4 and P2X7 and could be activated by different concentrations of extracellular ATP, which could be blocked by specific ion channel antagonists. In particularly, high concentration of ATP could induce mast cells to release inflammatory mediators such as histamine, IL-1β and CCL3 through P2X7 receptor. Furthermore, peripheral pain induced by high concentration of ATP could be alleviated by P2X7 blockers or mast cell defects. Interestingly, salicylic acid and aspirin could attenuate the inward current, the release of inflammatory factors and peripheral pain induced by ATP with high concentration. Furthermore, salicylic acid and aspirin also inhibited the inward current evoked by P2X7 agonist BZATP. Molecular docking results showed that salicylic acid and aspirin had affinity to the cytoplasmic GDP-binding region of P2X7.Conclusions We concluded that P2X7 on mast cells involved in peripheral pain. Salicylic acid and aspirin could inhibit the activity of P2X7 via interacting with the GDP binding region. P2X7 receptor was a potential target for salicylic acid and aspirin analgesia.

Native and IgE-primed rat peritoneal mast cells exert pro-inflammatory activity and migrate in response to yeast zymosan upon Dectin-1 engagement

Mast cells (MCs) play an essential role in host defense, primarily because of their location, their ability to pathogen destruction via several mechanisms, and the pattern recognition receptors they express. Even though most data is available regarding MC activation by various bacteria- or virus-derived molecules, those cells’ activity in response to constituents associated with fungi is not recognized enough. Our research aimed to address whether Saccharomyces cerevisiae-derived zymosan, i.e., β-(1,3)-glucan containing mannan particles, impacts MC activity aspects. Overall, the obtained results indicate that zymosan has the potential to elicit a pro-inflammatory response of rat peritoneal MCs. For the first time ever, we provided evidence that zymosan induces fully mature MC migration, even in the absence of extracellular matrix (ECM) proteins. Moreover, the zymosan-induced migratory response of MCs is almost entirely a result of directional migration, i.e., chemotaxis. We found that zymosan stimulates MCs to degranulate and generate lipid mediators (cysLTs), cytokines (IFN-α, IFN-β, IFN-γ, GM-CSF, TNF), and chemokine (CCL2). Zymosan also upregulated mRNA transcripts for several cytokines/chemokines with pro-inflammatory/immunoregulatory activity. Moreover, we documented that zymosan activates MCs to produce reactive oxygen species (ROS). Lastly, we established that the zymosan-induced MC response is mediated through activation of the Dectin-1 receptor. In general, our results strongly support the notion that MCs contribute to innate antifungal immunity and bring us closer to elucidate their role in host-pathogenic fungi interactions. Besides, provided findings on IgE-sensitized MCs appear to indicate that exposure to fungal zymosan could affect the severity of IgE-dependent disorders, including allergic ones.

Catechin synergistically potentiates mast cell-stabilizing property of caffeine

Caffeine and catechin, contained in coffee and tea, are commonly consumed substances worldwide. Studies revealed their health promoting functions, such as anti-oxidant, anti-cancer and anti-bacterial properties. Additionally, studies also revealed their roles in ameliorating the symptoms of allergic disorders, indicating their anti-allergic properties. In the present study, using the differential-interference contrast (DIC) microscopy, we examined the effects of caffeine and catechin on the degranulation from rat peritoneal mast cells. Both caffeine and catechin dose-dependently decreased the numbers of degranulating mast cells. At concentrations equal to or higher than 25 mM, caffeine and catechin markedly suppressed the numbers of degranulating mast cells. In contrast, at relatively lower concentrations, both substances did not significantly affect the numbers of degranulating mast cells. However, surprisingly enough, low concentrations of catechin (1, 2.5 mM) synergistically enhanced the suppressive effect of 10 mM caffeine on mast cell degranulation. These results provided direct evidence for the first time that caffeine and catechin dose-dependently inhibited the process of exocytosis. At relatively lower concentrations, caffeine or catechin alone did not stabilize mast cells. However, low concentrations of catechin synergistically potentiated the mast cell-stabilizing property of caffeine.

Tripterine: A Potential Anti-Allergic Compound

Background: Tripterine (TRI), an active monomer in Tripterygium wilfordii, has significant pharmacological activities, such as anti-inflammatory, immunosuppressive and anti-tumor activities. TRI may be used to treat allergic diseases because of its characteristics of immunosuppression. Objective: This study aims to explore the anti-allergic effect of TRI. Methods: It was tested in vivo and in vitro in this study. Results : The results showed that TRI could significantly inhibit histamine release from rat peritoneal mast cells; the inhibitory effect of TRI on histamine release was stronger than that of other known histamine inhibitors such as disodium cromoglyceride. TRI also significantly inhibited systemic anaphylactic shock induced by compound 48/80 and skin allergy induced by IgE, and inhibited the expression of inflammatory factors secreted by Human Mast Cells (HMC-1) induced by Phorbol 12-Myristate 13- Acetate (PMA) and calcium carrier A23187. In the animal model of allergic rhinitis induced by Ovalbumin (OA), the scores of friction, histamine, IgE, inflammatory factors and inflammatory cells decreased after TRI was administered orally or nasally. Conclusions : TRI, as an active immunoregulatory factor, has great potential in the treatment of mast cell-mediated allergic diseases.

Synthesis of Glycosides of α-Tocopherol, Daidzein, Resveratrol, Hesperetin, Naringenin, and Chrysin as Antiallergic Functional Foods and Cosmetics

Glucosyltransferase from Phytolacca americana (Phytolaccaceae), glucosylated α-tocopherol, daidzein, resveratrol, hesperetin, naringenin, and chrysin to α-tocopherol 6-β-d-glucoside, daidzein 7-β-d-glucoside, resveratrol 3-β-d-glucoside, hesperetin 7-β-d-glucoside, naringenin 7-β-d-glucoside, and chrysin 7-β-d-glucoside, respectively. The antiallergic activity of the glycosides and their aglycons was examined by an in vivo immunoglobulin E (IgE) antibody formation-suppression bioassay using rat. It was found that α-tocopherol 6-β-d-glucoside showed much higher antiallergic activity against glutenin than the positive control, hydrocortisone. On the other hand, daidzein 7-β-d-glucoside had much higher antiallergic activity toward 7S-globulin than hydrocortisone. These glycosides inhibited O2 − generation from rat neutrophils, which leads to the suppression of histamine release from rat peritoneal mast cells, resulting in the decrease of IgE antibody formation in rat. Chrysin 7-β-d-glucoside had stronger antityrosinase activity than chrysin. Cultured P. americana cells regioselectively introduced methoxyl and glucosyl residues on exogenously administrated chrysin to give 8-methoxychrysin and chrysin 7-β-d-glucoside. This is the first report on methoxylation of flavone compound at its eighth position by cultured plant cells.

P2X7 on Mast Cells Participates in Peripheral Pain and Serves as A Potential Target for Salicylic Acid and Aspirin Analgesia

Background Pain is an unpleasant sensory and emotional experience associated with actual or potential tissue damage. ATP is an important molecule closely related to many important physiological and pathologic functions. ATP-gated cation channel P2X receptors are widely distributed in various tissues of body, including nervous system and immune system. As an important member of P2X receptors, P2X7 is not only involved in pain, epilepsy, Parkinson’s diseases, but also in the formation of blood, respiratory and digestive diseases. In this study, we investigated the role of P2X receptors in mast cells for peripheral pain and the analgesic mechanism of salicylic acid and aspirin. Methods P2X receptors were examined and identified in mouse peritoneal mast cells by RT-PCR, intracellular calcium measurement and electrophysiology. The inflammatory mediators released from the activated mast cell were examined by real-time PCR and ELISA. Paw swelling, mechanical stimulation threshold and histopathological changes were tested to evaluate the peripheral pain in mice.Results The results showed that P2X1, P2X4, P2X7 receptors were expressed in mouse peritoneal mast cells. Mast cell was activated in a concentration-dependent manner by extracellular ATP, and the activation could be blocked by specific ion channel antagonists. In addition, high concentrations of ATP also induced mast cells to release inflammatory mediators such as histamine, IL-1β and CCL3 through P2X7 receptor. Furthermore, peripheral pain of the extracellular high concentration ATP to induce could be alleviated by P2X7 blockers or mast cell defects. We also found that salicylic acid and its derivation aspirin could inhibit high concentration ATP-induced inward current, release of inflammatory factors in mast cells, as well as the peripheral pain caused by high concentration ATP. Conclusions Together with these, we concluded that extracellular ATP with high concentration could not only activate neurons directly, but also activate P2X7 receptor on mast cells, and induce peripheral pain via neuro-immune crosstalk. Additionally, salicylic and aspirin could inhibit the activity of P2X7, therefore, P2X7 receptor may be one of the potential targets for salicylic acid and aspirin analgesia.

α1-Adrenergic Receptor Blockade by Prazosin Synergistically Stabilizes Rat Peritoneal Mast Cells

Background. Adrenaline quickly inhibits the release of histamine from mast cells. Besides β2-adrenergic receptors, several in vitro studies also indicate the involvement of α-adrenergic receptors in the process of exocytosis. Since exocytosis in mast cells can be detected electrophysiologically by the changes in the membrane capacitance (Cm), its continuous monitoring in the presence of drugs would determine their mast cell-stabilizing properties. Methods. Employing the whole-cell patch-clamp technique in rat peritoneal mast cells, we examined the effects of adrenaline on the degranulation of mast cells and the increase in the Cm during exocytosis. We also examined the degranulation of mast cells in the presence or absence of α-adrenergic receptor agonists or antagonists. Results. Adrenaline dose-dependently suppressed the GTP-γ-S-induced increase in the Cm and inhibited the degranulation from mast cells, which was almost completely erased in the presence of butoxamine, a β2-adrenergic receptor antagonist. Among α-adrenergic receptor agonists or antagonists, high-dose prazosin, a selective α1-adrenergic receptor antagonist, significantly reduced the ratio of degranulating mast cells and suppressed the increase in the Cm. Additionally, prazosin augmented the inhibitory effects of adrenaline on the degranulation of mast cells. Conclusions. This study provided electrophysiological evidence for the first time that adrenaline dose-dependently inhibited the process of exocytosis, confirming its usefulness as a potent mast cell stabilizer. The pharmacological blockade of α1-adrenergic receptor by prazosin synergistically potentiated such mast cell-stabilizing property of adrenaline, which is primarily mediated by β2-adrenergic receptors.

Synthesis of Daidzein Glycosides, α-Tocopherol Glycosides, Hesperetin Glycosides by Bioconversion and Their Potential for Anti-Allergic Functional-Foods and Cosmetics

Daidzein is a common isoflavone, having multiple biological effects such as anti-inflammation, anti-allergy, and anti-aging. α-Tocopherol is the tocopherol isoform with the highest vitamin E activity including anti-allergic activity and anti-cancer activity. Hesperetin is a flavone, which shows potent anti-inflammatory effects. These compounds have shortcomings, i.e., water-insolubility and poor absorption after oral administration. The glycosylation of bioactive compounds can enhance their water-solubility, physicochemical stability, intestinal absorption, and biological half-life, and improve their bio- and pharmacological properties. They were transformed by cultured Nicotiana tabacum cells to 7-β-glucoside and 7-β-gentiobioside of daidzein, and 3′- and 7-β-glucosides, 3′,7-β-diglucoside, and 7-β-gentiobioside of hesperetin. Daidzein and α-tocopherol were glycosylated by galactosylation with β-glucosidase to give 4′- and 7-β-galactosides of daidzein, which were new compounds, and α-tocopherol 6-β-galactoside. These nine glycosides showed higher anti-allergic activity, i.e., inhibitory activity toward histamine release from rat peritoneal mast cells, than their respective aglycones. In addition, these glycosides showed higher tyrosinase inhibitory activity than the corresponding aglycones. Glycosylation of daidzein, α-tocopherol, and hesperetin greatly improved their biological activities.