The Three-Herb Formula Shuang-Huang-Lian stabilizes mast cells through activation of mitochondrial calcium uniporter.

Mast cells (MCs) are key effector cells of IgE-FcεRI- or MrgprX2-mediated signaling event. Shuang-Huang-Lian (SHL), a herbal formula from Chinese Pharmacopoeia, has been clinically used in type I hypersensitivity. Our previous study demonstrated that SHL exerted a non-negligible effect on MC stabilization. Herein, we sought to elucidate the molecular mechanisms of the prominent anti-allergic ability of SHL. MrgprX2- and IgE-FcεRI-mediated MC activation in vitro and in vivo models were developed by using compound 48/80 (C48/80) and shrimp tropomyosin (ST), respectively. Our data showed that SHL markedly dampened C48/80- or ST-induced MC degranulation in vitro and in vivo. Mechanistic study indicated that cytosolic Ca (Ca) level decreased rapidly and sustainably after SHL treatment, and then returned to homeostasis when SHL was withdrawn. Moreover, SHL decreases Ca levels mainly through enhancing the mitochondrial Ca (Ca) uptake. After genetically silencing or pharmacologic inhibiting mitochondrial calcium uniporter (MCU), the effect of SHL on the Ca level and MC degranulation was significantly weakened. Simultaneously, the activation of SHL on Ca uptake was completely lost. Collectively, by activating MCU, SHL decreases Ca level to stabilize MCs, thus exerting a remarkable anti-allergic activity, which could have considerable influences on clinical practice and research.