The Journal of allergy and clinical immunology · 2024
MRGPRX2 facilitates IgE-mediated systemic anaphylaxis in a newly established knock-in mouse model.
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Bawazir Maram, Sutradhar Sangita, Roy Saptarshi, Ali Hydar
Аннотация
BACKGROUND: In addition to FcεRI, a subtype of human mast cells (MCs) expresses Mas-related G protein-coupled receptor X2 (MRGPRX2; mouse counterpart MrgprB2). Although MrgprB2 contributes to IgE-mediated passive systemic anaphylaxis (PSA) in vivo, an MRGPRX2 inhibitor, compound 9 (C9), does not block MrgprB2- or IgE-mediated MC degranulation in vitro.
OBJECTIVE: Our aim was to generate mice expressing human MRGPRX2 to study receptor function in vitro and PSA in vivo.
METHODS: The clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9-mediated gene editing approach was utilized to replace endogenous MrgprB2 with human MRGPRX2 in mice (MRGPRX2-KI mice). MRGPRX2 expression in the skin, gingiva, trachea, and colon were evaluated by using an anti-human MRGPRX2 antibody. Peritoneal MCs (PMCs) cultured from wild-type, MRGPRX2-KI, and MrgprB2-/- mice were used to study agonists-induced degranulation. The effects of selective MRGPRX2 inhibitors (C9 and compound 9-6 [C9-6]) on substance P- or IgE-mediated MC degranulation in vitro and IgE-mediated PSA in vivo were tested.
RESULTS: MRGPRX2-expressing MCs were present in tissues of MRGPRX2-KI mice. Most of the agonists tested induced greater degranulation at lower concentrations in PMCs from MRGPRX2-KI mice than in cells from wild-type mice. Furthermore, C9 and C9-6 inhibited degranulation in MRGPRX2-KI PMCs in response to substance P. In contrast, they had no effect on IgE-mediated degranulation in vitro but did inhibit PSA in MRGPRX2-KI mice in vivo.
CONCLUSIONS: MRGPRX2-KI mice provide a readily available source of primary MCs for signaling studies. Furthermore, transactivation of MRGPRX2 contributes to IgE-mediated PSA, suggesting that MRGPRX2-KI mice could be utilized as a preclinical model for testing novel therapeutics targeting MRGPRX2 and its cross talk with FcεRI.
OBJECTIVE: Our aim was to generate mice expressing human MRGPRX2 to study receptor function in vitro and PSA in vivo.
METHODS: The clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9-mediated gene editing approach was utilized to replace endogenous MrgprB2 with human MRGPRX2 in mice (MRGPRX2-KI mice). MRGPRX2 expression in the skin, gingiva, trachea, and colon were evaluated by using an anti-human MRGPRX2 antibody. Peritoneal MCs (PMCs) cultured from wild-type, MRGPRX2-KI, and MrgprB2-/- mice were used to study agonists-induced degranulation. The effects of selective MRGPRX2 inhibitors (C9 and compound 9-6 [C9-6]) on substance P- or IgE-mediated MC degranulation in vitro and IgE-mediated PSA in vivo were tested.
RESULTS: MRGPRX2-expressing MCs were present in tissues of MRGPRX2-KI mice. Most of the agonists tested induced greater degranulation at lower concentrations in PMCs from MRGPRX2-KI mice than in cells from wild-type mice. Furthermore, C9 and C9-6 inhibited degranulation in MRGPRX2-KI PMCs in response to substance P. In contrast, they had no effect on IgE-mediated degranulation in vitro but did inhibit PSA in MRGPRX2-KI mice in vivo.
CONCLUSIONS: MRGPRX2-KI mice provide a readily available source of primary MCs for signaling studies. Furthermore, transactivation of MRGPRX2 contributes to IgE-mediated PSA, suggesting that MRGPRX2-KI mice could be utilized as a preclinical model for testing novel therapeutics targeting MRGPRX2 and its cross talk with FcεRI.