A novel MRGPRX2-targeting antagonistic DNA aptamer inhibits histamine release and prevents mast cell-mediated anaphylaxis.

Anaphylaxis during general anaesthesia is a significant clinical challenge for anaesthesiologists. Approximately 50% of perioperative anaphylaxis cases lack the presence of specific IgE antibodies. Mas-related G-protein coupled receptor X2 (MRGPRX2) in humans and its mouse orthologue Mas-related G-protein coupled receptor B2 (Mrgprb2) are crucial receptors in non-IgE-dependent histamine release. Anaesthetics such as rocuronium and atracurium cause perioperative anaphylaxis by activating histamine release via the Mrgprb2 pathway. We hypothesized that antagonistic DNA aptamers that target MRGPRX2 can prevent perioperative anaphylaxis. Selection of a DNA aptamer that specifically binds MRGPRX2 was achieved by using our modified Systematic Evolution of Ligands by Exponential enrichment (SELEX) approach. Our SELEX process used MRGPRX2-proteoliposomes synthesised by a wheat germ cell-free system as templates. The activity of the selected aptamer to inhibit histamine release from MRGPRX2-activated mast cells and in an anaphylaxis rat model transplanted with this cell line was examined. Our selection process identified aptamer-X35 with the sequence 5'-ATGACCATGACCCTCCACACTGTAGGCACCACGGGTCCCTGGCAGTTAAAAGTACGTTTGTCAGACTGTGGCAGGGAAACA-3'. In silico 2D modelling of aptamer-X35 revealed a structure with a small loop and a long stem. Aptamer-X35 inhibited histamine release from mast cells by 70%. Subcutaneous injection of 30 nmol of aptamer-X35 inhibited the anaphylactic reaction in the rat anaphylaxis model. This study demonstrated that aptamer-X35 selected by the modified SELEX approach reduced histamine release by inhibiting the MRGPRX2 pathway. Overall, our findings establish aptamer-X35 as a potential therapeutic candidate against perioperative anaphylaxis.