Distinct non-coding RNA cargo of extracellular vesicles from M1 and M2 human primary macrophages

Purpose: Macrophages are often classified into M1 ‘classical’ and M2 ‘alternatively-activated’ macrophages. Extracellular vesicles (EVs) are biomolecule carriers involved in cell-cell communication. Here, we provide a first insight into the complete small RNA cargo of human macrophage M1/M2 EVs. Methods: Monocyte-derived macrophages were polarised into M1 (GM-CSF+LPS+IFNγ) or M2 (M-CSF+IL-4+IL-13) and EVs isolated by size exclusion chromatography. EVs were characterised by nanoparticle tracking analysis, electron microscopy and ELISA. EV RNA samples were prepared for small RNA sequencing using Qiagen’s GIAseq small RNA Library Prep kit and sequenced on an Illumina NextSeq500, single end 75 bp. Functional enrichment analysis was performed using MIENTURNET, based on validated miR-target interactions from miRTarBase. Results: Many types of small non-coding RNAs were found in EVs from M1/M2 macrophages including miRNAs, isomiRs, tRNA fragments, piRNA, snRNA, snoRNA and yRNA fragments. Distinct differences were observed between M1 and M2 EVs, with higher relative abundance of miRNAs, and lower abundance of tRNA fragments in M1 EVs compared to M2 EVs. MicroRNA-target enrichment analysis identified several gene targets involved in gene expression and metabolic processes. Conclusions: M1 and M2 cells release EVs with distinct tRNA and miRNA cargo, which have the potential to contribute to the unique effect of these cell subsets on their microenvironment. Small RNA sequencing of the RNA cargo of EVs from M1 and M2 primary monocyte derived macrophages