Expression of ferritin receptor in placental microvilli membrane in pregnant women with different iron status at mid-term gestation

Abstract

Objective: The effect of iron status in pregnant women on expression of ferritin receptor in placental microvilli membrane at mid-term gestation was investigated. Design: Ferritin receptor binding sites and dissociation constants (K d ) were determined in specimens of placental microvilli from 30 pregnant women at mid-term gestation and six women at term-delivery. Results: The ferritin receptor binding sites in the placental microvilli membrane in pregnant women with mild iron de®ciency and moderate iron de®ciency anemia were signi®cantly higher then those in pregnant women with normal iron status. However, no signi®cant difference was found between pregnant women with severe iron de®ciency anemia and with normal measurements. No signi®cant differences of K d values were detected between pregnant women with normal iron status and those with iron-de®ciency. Data also revealed that the ferritin receptor binding sites in placental microvilli membrane and K d values at mid-term gestation did not differ signi®cantly from those at term gestation. Conclusion: Lower iron status in pregnant women could lead to an increase in expression of ferritin receptor in placental microvilli membrane at mid-term gestation while the dissociation constant of ferritin receptor remains unchanged. This implies that the regulation of maternal ± fetal iron homeostasis via the ferritin receptor-mediated pathway is achieved by changes in the numbers of ferritin receptors rather then binding properties. Sponsorship: China Natural Science Foundation and The Hong Kong Polytechnic University. Descriptors: ferritin receptor; placental microvilli; iron status; pregnant women; maternal-fetal iron homeostasis

The placenta: the forgotten essential organ of iron transport

“…88,89 Electron microscopy of placental villi from ferritin-injected animals showed ferritin-containing endocytic vesicles 88 and ferritin accumulation in the basement membranes, 89 suggestive of ferritin endocytosis. This is consistent with human data showing specific ferritin binding by placental villous membranes 90,91 and appreciable amounts of ferritin-containing vesicles in the placenta. 31 The molecular mechanism of ferritin uptake by the placenta is unknown and may involve TFR1 92 and/or the renal ferritin receptor SCARA5 (scavenger receptor class A member 5).…”

Effects of dietary factors on iron uptake from ferritin by Caco-2 cells

“…However, Fe sequestered within the mineral core of Ft is unavailable to this transporter; thus, another mechanism for Ft-Fe uptake must exist. While the mechanism responsible for Fe uptake from Ft is not yet known, the presence of putative Ft receptors has been documented for several cell types [37][38][39][40][41][42], and we have preliminary data indicating receptor-mediated uptake of Fe from Ft by Caco-2 cells (Kalgaonkar & Lönnerdal, to be submitted).…”

Serum ferritin: Past, present and future

“…Thus experiments using intestinal Caco-2 cells indicated that enterocytes possess a ferritin receptor and absorb ferritin via a receptor-mediated (42). A ferritin receptor is also present on placental membranes (43). Interestingly, in pregnant women with mild or moderate iron deficiency, ferritin receptor binding sites are much more abundant than in pregnant women with normal iron status.…”