Gene Expression of CXCL1 (GRO-α) and EGF by Platelets in Myeloproliferative Neoplasms

We read with interest the recent publication by Øbro et al inHemaSphere documenting elevated cytokine levels in patients with myeloproliferative neoplasms (MPN). Specifically, their finding of a signature associated with essential thrombocythemia (ET) that included three biomarkers: GRO-a, EGF and eotaxin. GRO-a was of greatest interest as elevated levels were associated with disease transformation to myelofibrosis (MF). Further, based on intracellularflowcytometry, the source ofGRO-awas found to be CD56CD14 pro-inflammatory monocytes. Since GRO-a is stored within and secreted from platelet granules upon activation, the associated editorial hypothesizedwhether the circulatingGROa could be platelet-derived. We have explored this possibility, using a targeted next-generation sequencing approach, to assess whether the expression of genes encoding these cytokines is dysregulated in platelets from patients with MPN. We also assessedEGFand eotaxin todeterminewhether the changes seen in circulating levels have any platelet association in MPN subtypes. Blood was collected from 70 MPN patients (21 PV, 33 ET, 16 MF) and 15 controls, 40 of whom have been previously described. The project had ethical approval from the Sir Charles Gairdner Hospital (#2012–094, #2016–107) and University of Western Australia Human Research Ethics Committees (#RA/4/ 1/6566, #RA/4/1/9100), in accordance with the Declaration of Helsinki. Platelets were isolated, RNA extracted (miRNeasyMini Kit, Qiagen) and libraries prepared (Ion AmpliSeq Transcriptome Human Gene Expression Kit, ThermoFisher Scientific). Equimolar concentrations of barcoded libraries were pooled and underwent automated template preparation and sequenced on an Ion Proton Sequencer (ThermoFisher Scientific) using Ion

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