Human MRGPRX2 Stable Cell Line-HEK293

Polymyxin B (PMB) and polymyxin E (PME) are cyclic peptide antibiotics isolated from various strains of Bacillus polymyxa. Here, researchers report that human Mas-related G protein-coupled receptor X2 (MRGPRX2) and its murine homolog, Mas-related G protein-coupled receptor B2 (MrgprB2), are receptors that mediate the anaphylactoid responses induced by PMB and PME. They first investigated the anaphylactoid responses induced by PMB and PME in LAD2 cells in vivo and in vitro. They found that PMB and PME treatment led to a massive release of mast cell granules containing histamine and β-hexosaminidase, secretion of the proinflammatory cytokines TNF-α and PGD2, and stimulation of calcium flux in LAD2 cells. Furthermore, PMB and PME treatment reduced β-hexosaminidase release in MRGPRX2-knockdown LAD2 cells, while significantly increased calcium ion release in MRGPRX2-overexpressing HEK293 cells, suggesting that MRGPRX2 is involved in PMB- or PME-induced mast cell activation. In vivo, MRGPRX2-knockout mice exhibited less anaphylactic reactions than wild-type mice. MrgprB2 activation also caused increased capillary permeability and paw swelling. These results suggest that MRGPRX2 may be a potential therapeutic target for controlling anaphylactic reactions induced by PMB or PME.

Calcium release was detected in MRGPRX2 overexpressing HEK293 cells. The results showed that the Ca2+ concentration in cells treated with PMB and PME increased significantly (Figure 1a and b), while the Ca2+ concentration in HEK293 cells did not change. At the same time, the researchers measured the EC50 in MRGPRX2 overexpressing HEK293 cells. As can be seen from the curves, the EC50 in cells treated with PMB and PME were 8.9 μg/mL and 12.2 μg/mL, respectively (Figure 1c and d), which were much lower than the EC50 in cells treated with LAD2.

Figure 1. The changes in intracellular Ca2+ concentration in MRGPRX2 overexpressing HEK293 cells induced by PMB and PME. (Zhan Y, et al., 2019)