Luteolin inhibits FcεRΙ- and MRGPRX2-mediated mast cell activation by regulating calcium signaling pathways.

Luteolin is a flavonoid found in many fruits, vegetables, and herbs. The antiinflammatory effects of luteolin have been reported. In this study, the effect of luteolin on allergic diseases and the underlying molecular mechanism were investigated. We found that luteolin inhibits Fc epsilon RΙ (FcεRΙ)- and Mas-related G protein-coupled receptor X2 (MRGPRX2)-mediated mast cells (MCs) activation, including degranulation and release of cytokines in vitro. Moreover, luteolin reduces the degree of swelling and Evans blue exudation of mice paw in a dose-dependent manner. The concentrations of histamine, TNF-α, MCP-1, IL-8, and IL-13 in mice serum are also decreased by luteolin administration. Our study reveals that luteolin can inhibit FcεRΙ- and MRGPRX2-mediated allergic responses in vivo and in vitro, and our results discover luteolin inhibited mast cells mediated anaphylactic reaction by inhibiting the phosphorylation level of PLCγ.