2020.09.11 Journal club

Baicalin induces Mrgprb2-dependent pseudo-allergy in mice 

Jue Wanga, Yongjing Zhanga, Delu Chea, Yingnan Zenga, Yuanyuan Wub, Qiaohong Qinc, Nan Wanga,*

a School of Pharmacy, Xi’an Jiaotong University, Xi’an, 710061, China
b Department of Respiratory and Critical Care Medicine, The Second Affiliated Hospital of Xi’an Jiaotong University, Xi’an, 710061, China  c Institute of Basic and Translational Medicine, Xi’an Medical University, Xi’an, 710021, China

Baicalin, a component of traditional Chinese medicine, is one of the main compounds present in Scutellaria baicalensis Georgi. Pseudo-allergy induced by the injection of these medicines is a frequent adverse drug reaction. Therefore, elucidation of the anaphylactoid reaction of baicalin and its underlying mechanisms are important. Mast cells are primary effectors of allergic reactions, including pseudo-allergy. Studies have shown that Mrgprx2 in human mast cells is a specific receptor that is crucial for pseudo-allergic drug reactions, Mrgprb3 is the rat ortholog of human Mrgprx2, which in mice is designated as Mrgprb2. Here, we aimed to investigate baicalin- induced pseudo-allergy and the association of Mrgprb3 and Mrgprb2 with this effect. We examined the aller- genic effect of baicalin on RBL-2H3 cells and Mrgprb3-knockdown RBL-2H3 cells. Mrgprb2-expressing HEK293 cells and Mrgprb2-knockout mice were used to evaluate the role of Mrgprb2 in baicalin-induced allergy. Baicalin was found to dose-dependently induce pseudo-allergy both in vitro and in vivo. RBL-2H3 cells were activated by baicalin, whereas in Mrgprb3-knockout RBL-2H3 cells, baicalin showed a negligible effect on cell activation. Furthermore, baicalin activated the Mrgprb2-expressing HEK293 cells. Our data showed that baicalin did not induce allergy in Mpgprb2-knockout mice. We conclude that baicalin induces pseudo-allergy via Mrgprb2 in mice.

Keywords:Baicalin Pseudo-allergy Mrgprb2 Mrgprb3 Degranulation