Activation of human skin mast cells by vancomycin via MrgX2: Comparison to the effects of brimonidine

Abstract Vancomycin (VCM) is a glycopeptide antibiotic that inhibits bacterial peptidoglycan biosynthesis and is used for the treatment of certain Gram-positive bacterial infections of the eyes. However, the use of VCM is associated with several potential adverse reactions. We examined the mechanism of activation of human mast cells by vancomycin (VCM) and compared to brimonidine, an alpha2-adrenergic receptor agonist used to treat in glaucoma. VCM induced degranulation and cytokine secretion by SMCs, which were suppressed by pertussis toxin (PTX) (similar to MrgX2 ligands). Brimonidine induced less degranulation than VCM that was partially inhibited by PTX. MrgX2 expression on the surface of SMCs was detected by FACS analysis. VCM enhanced FceRI-mediated degranulation and cytokine secretion in a dose-dependent manner, whereas brimonidine failed to induce cytokine production and suppressed FceRI-mediated cytokine secretion. VCM induced maximal ERK-phosphorylation by 5 min similar to compound 48/80, an MrgX2 ligand and inhibited by PTX. VCM- but not brimonidine-induced degranulation of MCs was significantly inhibited by QWF, an MrgX2 antagonist. This study indicates that VCM but not brimonidine activates human SMCs via MrgX2 and that MCs become more responsive to VCM when co-stimulated by aggregating FceRI, which may occur when sensitive patients exposed to aeroallergen and VCM.