Involvement of MRGPRX2 signaling in Tween-80-induced pseudo-allergic reactions in mast cells

Tween-80 can induce severe pseudo-allergic reactions, but its mechanism is unclear. Mas-related G protein coupled receptor X2 (MRGPRX2) is a novel receptor that mediated pseudo-allergic reactions. The study aimed to determine whether MRGPRX2 signaling is involved in Tween-80-induced pseudo-allergic reactions.

With the treatment of Tween-80, degranulation of LAD2 mast cells transfected with specific MRGPRX2 siRNA was assayed by spectrophotometry, and paw swelling and extravasation were determined in wild-type and MrgprB2 knockout mice. Ca²⁺ mobilization and protein expression of signaling molecules were assayed by western blotting and laser confocal microscopy.

Tween-80 caused pseudo-allergic reactions in WT mice, but not in Kit^w-sh/w-sh mice, indicating mast cell dependency. In passive cutaneous pseudo-allergic test, Tween-80 vascular extravasation, paw swelling, mast cell degranulation, plasma histamine, and body temperature loss in wild‑type mice, whereas all these effects were inhibited in MrgprB2‑knockout mice, demonstrating that MrgprB2 (the mouse ortholog of MRGPRX2) is involved in the reaction. Consistently, in LAD2 cells, silencing MRGPRX2 with siRNA suppressed Tween‑80‑induced degranulation and Ca²⁺ influx. Tween‑80 also increased intracellular Ca²⁺ in MRGPRX2‑expressing HEK293 cells but not in HEK293 cells. Furthermore, Tween‑80 triggered Ca²⁺ mobilization and phosphorylation of Lyn, PLCγ, IP₃R, PKC, and p38 in LAD2 cells, and these responses were diminished by MRGPRX2 knockdown.

MRGPRX2 signaling is involved in Tween-80-induced pseudo-allergic reactions, likely through the Lyn/PLCγ/PKC/IP₃R and p38 pathways, whose activation appears to depend on MRGPRX2 and may contribute to mast cell degranulation. MRGPRX2 may be a potential therapeutic target for Tween-80-induced pseudo-allergic reactions.