UNLABELLED: Preeclampsia, a hypertensive disorder in pregnancy develops in 2-8% of pregnancies worldwide. Winter season and vitamin D deficiency have been associated with its onset.<br /><br />OBJECTIVE: To investigate the influence of season on maternal vitamin D status and placental vitamin D metabolism.<br /><br />METHODS: 25-OH vitamin D and 1,25-(OH)2 vitamin D were measured in maternal serum obtained during the winter or summer months from 63 pregnant women at delivery (43 healthy, 20 preeclampsia). In a subgroup, mRNA expression of CYP24A1 (24-hydroxylase), CYP27B1 (1α-hydroxylase) and VDR (vitamin D receptor) were quantified by real time PCR in placental samples of 14 women with normal pregnancies and 13 with preeclampsia.<br /><br />RESULTS: In patients with preeclampsia,25-OH vitamin D levels were lower, but differed significantly from controls only in summer (18.21±17.1 vs 49.2±29.2 ng/mL, P<0.001), whereas 1,25-(OH)2 vitamin D levels were significantly lower only in winter (291±217 vs 612.3±455 pmol/mL, P<0.05). A two-factorial analysis of variance produced a statistically significant model (P<0.0001) with an effect of season (P<0.01) and preeclampsia (P = 0.01) on maternal 25-OH vitamin D levels, as well as a significant interaction between the two variables (P = 0.02). Placental gene expression of CYP24A1, CYP27B1, and VDR did not differ between groups or seasons. A negative correlation between placental gene expression of CYP24A1 and CYP27B1 was observed only in healthy controls (r = -0.81, P<0.0001).<br /><br />SUMMARY: Patients with preeclampsia displayed lower vitamin D serum levels in response to seasonal changes.The regulation of placental CYP24A1, but not of the VDR or CYP27B1 might be altered in preeclampsia.
Lechtermann, C., Hauffa, B. P., Herrmann, R., Schündeln, M. M., Gellhaus, A., Schmidt, M., & Grasemann, C. (2014). Maternal vitamin D status in preeclampsia: Seasonal changes are not influenced by placental gene expression of vitamin D metabolizing enzymes. PLoS ONE, 9(8). https://doi.org/10.1371/journal.pone.0105558