Human placental trophoblasts synthesize melatonin and express its receptors

Abstract

Although the role of melatonin on fetal development has been the subject of a number of studies, little is known about the function of melatonin in the placenta. We previously showed that melatonin receptors are expressed and are functional in JEG-3 and BeWo cell lines, both in vitro models of human trophoblast. Local synthesis of melatonin in placenta has been proposed, but the human placenta's ability to synthesize melatonin de novo has never been studied. The purpose of this study was to investigate the expression [reverse transcription-polymerase chain reaction (RT-PCR) and western blot analysis] and activity (radiometric assay) of melatonin synthesizing enzymes, and characterize the expression of the melatoninergic receptors in human term villous trophoblast. The results show that arylalkylamine N-acetyltransferase and hydroxyindole O-methyltransferase melatonin synthesizing enzymes are expressed and active in villous trophoblast as well as in JEG-3 and BeWo placental choriocarcinoma cells. In addition, immunohistochemical analysis demonstrated the presence of MT1, MT2, and retinoid-related orphan nuclear receptor alpha melatonin receptor proteins in both villous cytotrophoblast and syncytiotrophoblast (STB) as well as in endothelial cells surrounding the fetal capillaries and in the villous mesenchymal core. RT-PCR and western blot analysis in primary cultures of human term trophoblast confirmed the expression of all three melatonin receptors in villous cytotrophoblast and STB cells. This study demonstrates for the first time a local synthesis of melatonin and expression of its receptors in human trophoblasts and strongly suggests a paracrine, autocrine, and/or intracrine role for this indolamine in placental function and development as well as in protection from oxidative stress.

The activating effect of IFN-γ on monocytes/macrophages is regulated by the LIF–trophoblast–IL-10 axis via Stat1 inhibition and Stat3 activation

“…Immediately after delivery, the placentas were immersed in DMEM-HG containing antibiotics (i.e., 5 mg/ml of amphotericin, 50 mg/ml of gentamycin and 0.12 mg/ml of penicillin), maintained at 4 uC and processed within 1 h. Villous cytotrophoblasts (vCTs) were isolated and purified as previously described by our group, using the trypsin-DNase/Percoll method. [39][40][41] Mononuclear vCTs were purified via immunomagnetic labelling using an autoMACS Myltenyi Biotec (Auburn, CA, USA) and an anti-HLA-ABC antibody, as described previously. 39 The purity of the immunopurified vCTs was determined via flow cytometry using a FITC-conjugated monoclonal antibody against cytokeratin-7.…”

“…[39][40][41] Mononuclear vCTs were purified via immunomagnetic labelling using an autoMACS Myltenyi Biotec (Auburn, CA, USA) and an anti-HLA-ABC antibody, as described previously. 39 The purity of the immunopurified vCTs was determined via flow cytometry using a FITC-conjugated monoclonal antibody against cytokeratin-7. All vCT preparations used in this study were at least 98% pure after cell sorting.…”

“…However, the possible interplay between LIF, trophoblast cells and IL-10 in the modulation of Mw functional phenotypes has never been investigated. Using in vitro Mw and trophoblast differentiation models that were previously established in our lab, [36][37][38][39][40][41] we investigate whether and how syncytiotrophoblast-derived factors in general and IL-10 in particular regulate the effects of IFN-c on the behavior of Mws in response to LIF stimulation and describe the mechanism of action of these factors at the molecular level.…”

Breastfeeding and the gut-brain axis: is there a role for melatonin?

“…Over the course of pregnancy, the placenta produces increasing levels of melatonin, in a non-circadian fashion (27). The melatonergic pathways are, therefore, activated throughout pregnancy, with beneficial effects in both the mother and the fetus as well as the placenta (95).…”

“…Melatonin has been most widely investigated following its nighttime release by the mammalian pineal gland, a process that intimately involves melatonin in circadian rhythm regulation (25). However, melatonin is produced by an array of cell types, including astrocytes, placental trophoblasts, immune cells and enterochromaffin gut cells (26)(27)(28)(29). Following a meal, gut melatonin synthesis can be 400-fold that of the pineal gland night-time peak release (30).…”