Applying label-free dynamic mass redistribution assay for studying endogenous FPR1 receptor signalling in human neutrophils

Introduction: The label-free dynamic mass redistribution-based assay (DMR) is a powerful method for studying signalling pathways of G protein-coupled receptors (GPCRs). Herein we present the label-free DMR assay as a robust readout for pharmacological characterization of formyl peptide receptors (FPRs) in human neutrophils. Methods: Neutrophils were isolated from fresh human blood and their responses to FPR1 and FPR2 agonists, i.e. compound 43, fMLF and WKYMVm were measured in a label-free DMR assay using Epic Benchtop System from Corning (R). Obtained DMR traces were used to calculate agonist potencies. Results: The potencies (pEC(50)) of fMLF, WKYMVm and compound 43, determined on human neutrophils using the label-free DMR assay were 8.63, 7.76 and 5.92, respectively. The DMR response to fMLF, but not WKYMVm and compound 43 could be blocked by the FPR1-specific antagonist cyclosporin H. Discussion: We conclude that the DMR assay can be used, and complements more traditional methods, to study the signalling and pharmacology of endogenous FPR receptors in human neutrophils.