Objectives: To better understand the molecular mechanism of human placental iron transfer, the protein and mRNA expression of iron transporters, transferrin receptor 1 (TfR1), ferritin and ferroportin 1 (FP1) were examined simultaneously.
Study design: Forty pregnant women, 18 normal, 22 with anemia but all free from other medical conditions, were chosen for the research and their iron status was determined before delivery. Forty human term placentas were collected from these pregnant women with different iron status in the third trimester. The protein and mRNA expression of iron transporters in the placental tissues were assessed by means of Western blot and real-time quantitative PCR.
Results: The study showed that the expression of TfR1 mRNA increased significantly (almost three-fold) in the mild anemia group and decreased near to the normal level in the moderate anemia group. The same trend was observed for TfR1 protein expression, but it was not statistically significant. Ferritin protein expression decreased slightly in the mild anemia group but significantly in the moderate anemia group (almost two-fold). L-ferritin mRNA expression increased slightly in the mild anemia group and H-ferritin mRNA reduced gradually with the aggravation of the maternal anemia, but neither showed statistical significance. No significant change in either protein or mRNA expression of FP1 was observed in the maternal anemia groups.
Conclusion: The expression of TfR1, ferritin and FP1 in the human term placenta tissues showed different trend of change with different maternal iron status. It revealed that a human placenta has the function to protect a fetus through regulating the expression of iron transporters. The expression of FP1 in a human placenta may not be regulated by the iron responsive element/iron regulatory protein (IRE/IRP) system. In addition to FP1, other proteins may be involved in the placental iron efflux either directly or indirectly.