Vasoactive intestinal peptide shapes first‐trimester placenta trophoblast, vascular, and immune cell cooperation

Abstract

Background and Purpose: Extravillous trophoblast (EVT) cells are responsible for decidual stromal invasion, vascular transformation, and the recruitment and functional modulation of maternal leukocytes in the first-trimester pregnant uterus. An early disruption of EVT function leads to placental insufficiency underlying pregnancy complications such as preeclampsia and fetal growth restriction. Vasoactive intestinal peptide (VIP) is a vasodilating and immune modulatory factor synthesized by trophoblast cells. However, its role in first-trimester placenta has not been explored. Here, we tested the hypothesis that VIP is involved in first-trimester EVT outgrowth, spiral artery remodelling, balancing angiogenesis, and maintenance of immune homeostasis.Experimental Approach: First-trimester placental tissue (five to nine weeks of gestation) was collected, and was used for EVT outgrowth experiments, immunofluorescence, isolation of decidual natural killer (dNK) cells and decidual macrophages (dMA), and functional assays. Peripheral blood monocytes were differentiated with GM-CSF and used for angiogenesis assays.Key Results: In decidua basalis, VIP+ EVT were observed sprouting from cell columns and lining spiral arterioles. EVT migrating from placental explants were also VIP+. VIP increased EVT outgrowth and IL-10 release, whereas it decreased proinflammatory cytokine production in EVT, dNK cells, and dMA. VIP disrupted endothelial cell networks, both directly and indirectly via an effect on macrophages. Conclusion and Implications:The results suggest that VIP assists the progress of EVT invasion and vessel remodelling in first-trimester placental bed in an immunologically "silent" milieu. The effects of VIP in the present ex vivo human placental model endorse its potential as a therapeutic candidate for deep placentation disorders.

Vasoactive Intestinal Peptide induces glucose and neutral amino acid uptake through mTOR signalling in human cytotrophoblast cells

“…Our results clearly support this proposal since VIP increased the transport of glucose and amino acids in two human trophoblast-derived cells lines (Swan 71 and BeWo) that share many characteristics of cytotrophoblast cells and having the BeWo cells the ability to syncytialize. The concentration range of VIP to modulate glucose and amino acid uptake shown here is the same as that recently reported for the migration and invasion of human trophoblast cell lines 29 as well as for trophoblast migration in primary cultures of human first trimester placental explants 31 . Accordingly, VIP concentrations used here are consistent with VPAC1 and VPAC2 receptor-mediated effects, both subtypes expressed on Swan 71 and BeWo cytotrophoblast cells 31,37 .…”

“…On the basis that trophoblast cells synthesize VIP 29,35 and that VIP regulates cytotrophoblast cell function through autocrine loops 29 , loss of function experiments were next carried out to investigate the relevance of endogenous VIP in the regulation of trophoblast glucose uptake. We performed knocking down experiments using a VIP siRNA in Swan 71 and BeWo cells for 72 h, and after confirming the decrease of VIP expression to less than 50% compared to scramble-transfected cells as previously 29,31 , 2-NBDG incorporation was measured by flow cytometry. The results shown in Figure 2c indicate that VIP silencing reduced 2-NBDG uptake in both cell lines suggesting the involvement of endogenous VIP in glucose transport in trophoblast cells.

Figure 1Characterization of 2-NBDG uptake and the effect of VIP in trophoblast cells.

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“…In the Swan 71 and the HTR8/SVneo human cytotrophoblast cell lines, VIP promotes trophoblast cell migration and invasion through CRE-PKA pathways 29 . In line with an active role of endogenous VIP in cytotrophoblast cell regulation, VIP knocked-down cells presented lower expression of metalloproteases 31 , reduced basal and LIF-mediated migration 29 as well as they failed to regulate the functional phenotype of maternal leukocytes 32 . Regarding trophic effects of VIP, it displayed an embryotrophic effect on mouse embryos explanted with their yolk sacs at day 9.5 39 whereas lower birth-weight pups were born from mothers deficient in VIP compared to wild type mice 48 .…”

VIP Promotes Recruitment of Tregs to the Uterine–Placental Interface During the Peri-Implantation Period to Sustain a Tolerogenic Microenvironment

“…During the first trimester, the deciduochorial state confirmed the importance of these secretions for normal development of the conceptus (56,57). In line with this, intense immunolabelling of VIP was recently demonstrated in exocrine glands of human first-trimester placenta (22).…”

“…One of the factors proposed to have an immunoregulatory role during implantation and at the early maternal-fetal interface is vasoactive intestinal peptide (VIP) (18,19). VIP is produced by stromal cells (20), syncytium, and cytotrophoblastic cells in the first and third trimesters (21) by extravillous trophoblast (EVT) cells and decidual glandular cells (22,23). VIP is an endogenous 28-amino acid peptide with strong anti-inflammatory and vasodilating activities by binding to the high-affinity specific VPAC1 and VPAC2 receptors (24)(25)(26).…”