665 Pruritogen activation of human MRGPRX2

Abstract

Histamine-independent mechanisms mediate the itch associated with the majority of dermatologic and systemic diseases. SLIGRL is a prototypic histamine-independent pruritogen. It is derived from the tethered sequence of the PAR2 receptor. Previous studies have demonstrated that SLIGRL activates mouse MrgprC11 to induce itch. We demonstrate that SLIGRL specifically activates human MRGPRX2, a receptor implicated in itch, allergy, and inflammation. We also evaluated the effect of QWF, an MRGPRX2 antagonist, on SLIGRL-induced activation of Mrgprs and SLIGRL-induced itch in mice. The in vitro interactions of SLIGRL and QWF with Mrgprs were studied using HEK-293 cells transfected with cDNAs encoding mouse MrgprC11, human MRGPRX1, MRGPRX2 MRGPRX3, and MRGPRX4. Intracellular calcium ([Ca2+]) was determined by ratiometric Fura-2 imaging as an indicator of receptor activation. For in vivo experiments, the mouse cheek model, which differentiates between itch and pain, was used to evaluate the effect of QWF on SLIGRL-induced itch in C57BL/6 mice. Consistent with previous studies, SLIGRL activates mouse MrgprC11. We demonstrate that SLIGRL specifically activates human MRGPRX2. The MRGPRX2 antagonist, QWF inhibits activation HEK-293 cells expressing mouse MrgprC11 and human MRGPRX2. SLIGRL-induced itch is significantly decreased (p<0.05), to baseline, with QWF. In conclusion, SLIGRL activates human MRGPRX2, a receptor implicated in itch, allergy, and inflammation. Receptor activation is blocked by QWF. Antagonists of human MRGPRX2 may have therapeutic role in the treatment of itch, allergy and inflammation.