Effects and mechanism of anaphylactoid reaction induced by nonapeptide activating mast cells / 中国药房

OBJECTIVE To study the effects and potential mechanism of anaphylactoid reaction induced by nonapeptide IVQKIKHCF activating mast cells. METHODS Using human mast cell line LAD2 as subject， and substance P as positive control， the activation effects of 25， 50 and 100 μmol/L IVQKIKHCF on mast cells were investigated by determining the release rate of β-aminohexosidase， histamine release， and the contents of inflammatory factors； using MrgprX2-knockdown LAD2 cells and Mas- related G protein-coupled receptor X2 （MRGPRX2） high-expression human embryonic kidney cell line HEK293 （MRGPRX2/ HEK293 cells） as subject， the correlation between the activation effect of IVQKIKHCF and MRGPRX2 was investigated by determining the release rate of β-aminohexosidase， and intracellular calcium ion concentration. RESULTS IVQKIKHCF with 25， 50， 100 μmol/L could significantly increase the release rate of β-aminohexosidase and histamine release in LAD2 cells （P＜0.05）， and promote the release of tumor necrosis factor-α， interleukin-8， macrophage inflammatory protein-1β and monocyte chemotactic protein-1 to varying degrees （P＜0.05）. After knocking down MrgprX2， the effects of 25， 50， 100 μmol/L IVQKIKHCF promoting the release of β-aminohexosidase in LAD2 cells were reversed significantly （P＜0.05）， resulting in an increase of calcium ion concentration in MRGPRX2/HEK293 cells. CONCLUSIONS Nonapeptide IVQKIKHCF can promote mast cells to release granular matter and inflammatory mediators by activating MRGPRX2 thus inducing anaphylactoid reaction.

Anti-pseudo-allergic components in licorice extract inhibit mast cell degranulation and calcium influx / 中国天然药物

Pseudo-allergic reactions (PARs) widely occur upon application of drugs or functional foods. Anti-pseudo-allergic ingredients from natural products have attracted much attention. This study aimed to investigate anti-pseudo-allergic compounds in licorice. The anti-pseudo-allergic effect of licorice extract was evaluated in rat basophilic leukemia 2H3 (RBL-2H3) cells. Anti-pseudo-allergic compounds were screened by using RBL-2H3 cell extraction and the effects of target components were verified further in RBL-2H3 cells, mouse peritoneal mast cells (MPMCs) and mice. Molecular docking and human MRGPRX2-expressing HEK293T cells (MRGPRX2-HEK293T cells) extraction were performed to determine the potential ligands of MAS-related G protein-coupled receptor-X2 (MRGPRX2), a pivotal target for PARs. Glycyrrhizic acid (GA) and licorice chalcone A (LA) were screened and shown to inhibit Compound48/80-induced degranulation and calcium influx in RBL-2H3 cells. GA and LA also inhibited degranulation in MPMCs and increase of histamine and TNF-α in mice. LA could bind to MRGPRX2, as determined by molecular docking and MRGPRX2-HEK293T cell extraction. Our study provides a strong rationale for using GA and LA as novel treatment options for PARs. LA is a potential ligand of MRGPRX2.

Preliminary study on the mechanism of anaphylactoid reaction induced by natural product germacrone / 药学学报

The Chinese medicine injections prepared by the natural products containing sesquiterpenoids caused various adverse reactions in clinical use, among which skin allergic reactions are the most common. However, whether the reason of allergic reaction was related to the three isoprene units contained in the sesquiterpenoids is not clear, so the evaluation of drug safety has important guiding significance. The sesquiterpenoids are small molecular substances, and they are not antigens or haptens. They may induce anaphylaxis reactions by acting mast cells directly. Current research confirmed that Mas-related G protein-coupled receptor-X2 (MRGPRX2) which is a 7-transmembrane G protein coupled receptor on mast cells was a key target mediated allergic reactions induced by many small molecular drugs. Unlike IgE-mediated allergic reactions, pseudo-allergic reaction is related to dosage and dosing rate, and occurs in the first exposure to the sensitizer. In this paper, a series of experiments in vitro found that not all sesquiterpenoids caused anaphylactoid reactions. Ginsenoside Re, ginsenoside Rb1 and germacrone were selected as representative of sesquiterpenoids for calcium imaging assay. The data confirmed that only germacrone activated calcium mobilization through MRGPRX2, causing an increase in intracellular calcium ion concentration in mast cells. Furthermore, the release rate of β-hexosaminidase and the release amount of histamine analysis confirmed that germacrone induced mast cells degranulation directly. Knockdown of MRGPRX2 expression by siRNA and competitive binding experiments against ciprofloxacin were used to prove the target of germacrone was MRGPRX2. The results indicated that germacrone could activate mast cells directly to induce anaphylactoid reaction via MRGPRX2, which might be the reason of skin allergic reactions caused by injections containing germacrone.