Severe Early-Onset Preeclampsia Is Not Associated with a Change in Placental Catechol O-Methyltransferase (COMT) Expression

The genetic deletion of catechol O-methyltransferase (COMT) in mice produces a preeclampsia-like phenotype, with mice exhibiting hypertension, proteinuria, and histological changes, consistent with human pathological features. 2-Methoxyoestradiol, a metabolite of COMT, increases human trophoblast invasiveness in vitro under hypoxic conditions, providing further support that decreased COMT expression may have a role in preeclampsia. However, evidence confirming decreased COMT expression in human disease has been limited to small studies of placentas obtained from cases of term preeclampsia. We examined COMT expression in placentas obtained from healthy term pregnancies (n = 14), preterm nonmotensive pregnancies (n = 8), and pregnancies complicated by severe preterm preeclampsia (delivery at <34 weeks' gestation; n = 22). Among our preeclamptic cohort were 10 pregnancies further complicated by HELLP syndrome (hemolysis, elevated liver enzymes, and low platelets); and one pregnancy complicated by an eclamptic seizure. COMT expression was analyzed by RT-PCR, Western analysis, and IHC. COMT was mainly expressed in the syncytiotrophoblast. We did not find a significant difference in placental COMT expression in severe preeclampsia compared with either term or preterm normotensive cohorts. Our results suggest that severe preeclampsia may not be associated with a decrease in placental COMT expression. (Am J Pathol 2011, 178:2484-2488; DOI: 10.1016/j.ajpath.2011.02.029)