Abstract
We found 9 proteases in human placenta. Our studies showed that these placental proteasesmetabolize vasoactive and immunomodulating peptides, possibly derived from the fetus, and protect the exchange of peptide hormones across the placenta in order to maintain feto-placental homeostasis. We clarified the pregnancy serum oxytocinase discovered by Fekete in 1930 and angiotensinase by Page in 1947, respectively. In addition we showed the pregnancy serum bradykininase. Changes in maternal serum protease activities were useful for monitoring of pre-elcampsia and predicting the onset of labor. In addition, the ratio of peak systolic over least diastolic pressure of uterine or umbilical artery assessed by the Doppler technique was closely correlated with the levels of maternal serum proteases in preeclampsia, which suggested that placental proteases might control uteroplacental circulation via the regulation of concentrations of vasoactive peptides in uteroplacental circulation. The degradation of immunomodulating peptides by placental protease also suggests the possible involvement of placental protease in the immunological aspect of pregnancy.
