Label-free Proteomic Analysis of Exosomes Secreted from THP-1-Derived Macrophages in the Absence or Presence of Interferon-α

Exosomes are extracellular vesicles that function in intercellular communication. We have previously reported that exosomes play a role in the transmission of antiviral molecules during interferon-α (IFN-α)-mediated immune responses. In this study, the protein contents of THP-1-derived macrophages with or without interferon-α treatment and of the exosomes secreted from these cells were analyzed by the label-free LC-MS/MS quantitation technologies. A total number of 1845 and 1550 protein groups were identified in the THP-1 macrophages and the corresponding exosomes, respectively. Treating the cells with IFN-α resulted in the differential abundance of 110 proteins in cells and 260 proteins in exosomes (greater than 2.0-fold), among which 35 proteins were both up-regulated in the IFN-α treated cells and corresponding exosomes while 139 proteins were specifically up-regulated in exosomes but not in the donor cells. GO and KEGG analysis of the protein function categories suggested that IFN-α promoted the abundance of proteins involved in “defense response to virus” in both exosomes and cells, and proteins related to “RNA processing” only in exosomes. Functional analysis further indicated that exosomes from IFN-α-treated cells exhibited potent antiviral activity that restored the impaired antiviral response of IFN-α in hepatitis B virus-replicating hepatocytes. These results have deepened the understanding of the exosome-mediated transfer of IFN-α-induced antiviral molecules and may provide new basis for therapeutic strategies to control viral infection.