Characterization of mRNA Profiles of Exosomes from Diverse Forms of M2 Macrophages

Exosomes transmit certain amounts of molecules to specific recipient cells for intercellular communication. Among these molecules, messenger RNAs (mRNAs) may be delivered and translated into proteins in the recipient cells, and these mRNAs are thought to be critical mediators of exosomal functions. There are three subtypes of M2 macrophages (M₂Ф), M_2aФ, M_2bФ, and M_2cФ, which have different specific functional programs. The aim of the present study was to screen the mRNA profiles in the exosomes of these macrophage subtypes and to analyze the transcriptomic profile features associated with their specific functions. The mRNA contents of the exosomes isolated from the culture supernatants of the M₂Ф subtypes were analyzed and compared using the Illumina HiSeq platform. The results indicated that the exosomes contained particular mRNAs from their source cells and were messengers of cellular functions. Bioinformatics analysis suggested that the exosomal mRNAs from M_2bФs are enriched in the Toll-like receptor (TLR), tumor necrosis factor (TNF), NOD-like receptor (NLR), and NF-kappa B (NF-κB) signaling pathways. The mRNA profile of exosomes from M_2bФ was distinctly different from that of exosomes from M_2aФ and M_2cФ and was consistent with the M_2bФ cytological characteristic of maintaining a high level of proinflammatory cytokine and regulatory factor production. Therefore, the mRNA profiles revealed several characteristics of the exosomes from diverse forms of M₂Ф. Further functional investigations based on these results may advance the understanding of the physiological roles of exosome-transferred mRNAs in MФ functions.