MRGPRX2 and Immediate Drug Hypersensitivity: Insights From Cultured Human Mast Cells.

BACKGROUND AND OBJECTIVES: Mast cell (MC) degranulation via activation of the Mas-related G protein-coupled receptor X2 (MRGPRX2) plays a key role in immediate drug hypersensitivity (IDH). However, data in humans are limited to observations in specific cell lines. Objective: To study the usefulness of silencing MRGPRX2 in human MCs with the aim of further unveiling the MRGPRX2 pathway in IDH. METHODS: MCs were cultured from CD34+ progenitor cells obtained from peripheral blood (PBCMCs) and incubated with substance P (as a positive control), rocuronium, moxifloxacin, morphine, or amoxicillin. Immunophenotyping of the cells included flow cytometry and microscopy analyses of the expression of CD117, CD203c, and MRGPRX2. Intracellular calcium was measured using Fluo-4. Degranulation was analyzed by quantifying CD63 expression. For MRGPRX2 silencing, MCs were electroporated with Dicer small interference RNAs. RESULTS: Incubation of MCs with substance P, morphine, and moxifloxacin increased intracellular calcium levels and triggered MC degranulation, which, for the drugs, is almost completely abolished by selective MRGPRX2 silencing. Despite an increase in intracellular calcium in MRGPRX2+ cells, incubation with nontoxic concentrations of rocuronium does not result in degranulation of PBCMCs. Amoxicillin has no effect on PBCMCs. CONCLUSION: The use of MRGPRX2 silencing in human MCs can provide important insights into the role of MRGPRX2 in the pathogenesis of IDH. As induction of calcium signals does not necessarily translate into a secretory response, measurement of the degranulation reaction seems more meaningful in the context of drug testing.

Measurable Serum Estradiol and Estrone in Women 36-56 Years During Adjuvant Treatment With Aromatase Inhibitors for a Hormone Receptor-Positive Breast Cancer. Case Studies and Cross-sectional Study Using an Ultra-sensitive LC-MS/MS-Method.

BACKGROUND AND PURPOSE: Ovarian function recovery (OFR) during adjuvant use of an aromatase inhibitor (AI) negatively impacts breast cancer outcome. We measured serum FSH and estrogen levels in consecutive AI-users with an uncertain menopausal status during follow-up and report associated risk factors of OFR METHODS: A retrospective cross sectional observational monocentric study including breast cancer patients in follow-up using an adjuvant AI, age 36 to 56 years, with at least one serum estradiol (E2) and estrone (E1) measurement between 2013 and 2020. Estrogens were quantified using a sensitive liquid chromatography-tandem mass spectrometry method (LC-MS/MS). Women on LHRH agonist were included while those with a bilateral oophorectomy or ovarian irradiation were not. We aimed to identify risk factors of OFR considering age, body mass index (BMI), previous chemotherapy and duration of AI use. Univariable analysis was used to evaluate risk factors of OFR. RESULTS: E2/E1 levels were assessed in 207 patients with a median age of 50 years (range 36-56). 17 of 159 on AI (10.7%) and 3 of 48 on AI + LHRH (6.3%) had OFR. Seven out of 17 patients (41,2%) with OFR in the AI only group and 2 out of 3 patients (66,7%) in the AI+LHRH agonist group were in amenorrhea. Age <50 y and adjuvant chemotherapy were statistically significantly different between the OFR group and the group with postmenopausal estrogen levels. CONCLUSION: Breast cancer patients aged 36 to56 years need to be monitored closely during adjuvant treatment with aromatase inhibitors: to confirm menopausal status, to evaluate compliance and to ensure ovarian activity remains adequately suppressed. Estrone might be a better marker then estradiol to detect ovarian reactivation.