Benoit Barbeau, PhD
Professor, Université du Québec à Montréal
research axis 3
Our research interests are focussed on human exogenous retroviruses, such as HIV-1 and HTLV viruses and human endogenous retroviruses (hERV) in relation to their implication in the formation of the human placenta. We are currently conducting a series of studies aimed at the understanding of their role in placental functions and we are particularly concentrating our efforts on their association to obstetrical disorders, such as preeclampsia. Our efforts are first being centered on the regulation of these genes and of their mouse equivalent in placental cells, though the study of transcriptional and post-transcriptional regulatory mechanisms. Secondly, our research team conducts a series of studies on placenta-derived exosomes. We have shown that, in pregnant women, these circulating microvesicles harboured Syncytin-1 and Syncytin-2, two hERV-derived proteins, on their surface. Alike for ancestral viruses, these proteins seem to provide a tropism to placental exosomes, and are thereby targeting their internalization by specific cell types expressing appropriate receptors on their surface. In addition, our results have suggested that Syncytin-2 levels are lower in serum-derived exosomes from pre-eclamptic women than in exosomes from normal pregnant women. These latter results argue for the potential future development of an early diagnostic tool for preeclampsia predisposition through the detection of Syncytin-2 in serum exosomes. Further experiments are currently aimed at looking at how expression of different hERV envelope proteins in placental cells might equally influence exosome targeting and determining how extensive does hERV envelope proteins contribute to targeting a wide variety of cell types. In this context, the impact of hERV envelope-containing exosomes on differentiation states of villous/extravillous cytotrophoblasts and human endothelial cells and the activation state of immune cell populations, such as CD4+ and Cd8+ T cells, Treg, NK and DC cells become of high interest toward pregnancy and obstetric disorders linked to the placenta. The impact of other cellular factors, such as galectin-1 and tetherin on exosomes binding and release are also being closely examined.