Exosomes Transport Anti-Human Immunodeficiency Virus Factors from Human Cervical Epithelial Cells to Macrophages.

The female reproductive tract (FRT) is a major site of HIV sexual transmission. As the outermost layer of cells in the FRT, the human cervical epithelial cells (HCEs) have direct contact with HIV or infected cells. Our early work showed that supernatant (SN) from TLR3-activated HCEs contain the antiviral factors that could potently inhibit HIV replication in macrophages. However, it remains to be determined how HCEs transport the anti-HIV factors to macrophages. This follow-up study examined the role of exosomes in HCE-mediated anti-HIV activity. We found that TLR3 activation of HCEs resulted in the release of exosomes that contained multiple IFN-stimulated genes (ISGs: ISG56, OAS1, MxA, and Mx2) and the HIV restriction microRNAs (miR-28, miR-29 family members, miR-125b, miR-150, miR-382, miR-223, miR-20a, and miR-198). The depletion of exosomes from SN of TLR3-activated HCEs diminished HCE-mediated anti-HIV activity in macrophages, indicating that HCE-derived exosomes are responsible for transporting the antiviral molecules to macrophages. These in vitro findings suggest a novel antiviral mechanism by which HCEs participate in the FRT innate immunity against HIV infection. Further in vivo studies are necessary in order to develop an exosome-based delivery system for prevention and treatment of HIV infection through sexual transmission.