Small but Effective: Trophoblast-Derived miRNAs Transported Via Exosomes as Guardians Against Viral Infections

Abstract

Evaluation of: Delorme-Axford E, Donker RB, Mouillet JF et al. Human placental trophoblasts confer viral resistance to recipient cells. Proc. Natl Acad. Sci. USA 110(29), 12048–12053 (2013). Chromosome 19 miRNA cluster (C19MC) is the largest human miRNA cluster. It is almost exclusively expressed in extraembryonic tissue, particularly of the placenta. Its miRNAs may not only act locally, but, being released to the maternal circulation in large amounts, may also affect other tissues. Recently, Delorme-Axford et al. showed that C19MC miRNAs contribute to viral resistance in the trophoblast and confer this resistance to several other cells via exosomes. Furthermore, they provide strong evidence that this antiviral activity is based on the induction of autophagy in the target cells. These findings indicate a pivotal role of C19MC miRNAs in pregnancy by counteracting embryonal and fetal infections and, simultaneously, raise several further questions, including therapeutic approaches.