Over the last few years, vitamin D deficiency (VDD) was inconsistently reported to be linked to the development of preeclampsia. Osteopontin is an adhesion molecule necessary for trophoblastic invasion, a process which is defective in preeclampsia. As vitamin D was shown to affect osteopontin expression in different tissues, this study investigated this relation in preeclampsia.
Patients and methods
Gestational age-matching (32–40 weeks) controls (n=51) and preeclamptic pregnancies (n=51) were enrolled in this case–control study. Preeclampsia was subdivided into mild, early-onset, and late-onset severe preeclampsia (EOSPE and LOSPE). Serum levels of vitamin D were assessed. The intensity and distribution of osteopontin were immunohistochemically evaluated in extravillous cytotrophoblasts.
Vitamin D deficiency was widely prevalent among the women studied (90.2%, n=92). Both VDD and osteopontin accumulation were more prominent in preeclampsia versus controls (P<0.001 for both), in EOSPE and LOSPE versus controls before and beyond 34 weeks, respectively (P<0.001) and in severe vs. mild preeclampsia (P=0.004 and 0.03 for VDD and osteopontin). Vitamin D levels correlated significantly with osteopontin expression, both in preeclampsia (r=−0.592043, P<0.001) and controls (r=−0.339094, P=0.008). Multiple regression analysis confirmed an association between osteopontin expression and VDD, independent of the gestational age, in EOSPE and LOSPE (P=0.03 vs. 0.77 and P=0.02 vs. 0.38, respectively). In mild preeclampsia and controls, both VDD and gestational age affected osteopontin expression.
The correlation between VDD and higher expression of osteopontin in extravillous trophoblasts may represent one of the underlying mechanisms linking vitamin D to preeclampsia.