PHYSIOLOGICAL-ROLE OF PLACENTAL PROTEASES - INTERACTION BETWEEN PREGNANCY-INDUCED BIOACTIVE PEPTIDES AND PROTEASES

We found 9 proteases in human placenta. Our studies showed that these placental proteases metabolize vasoactive and immunomodulating peptide s, possibly derived from the fetus, and protect the exchange of peptid e hormones across the placenta in order to maintain fete-placental hom eostasis. We clarified the pregnancy serum oxytocinase discovered by F ekete in 1930 and angiotensinase by Page in 1947, respectively. In add ition 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 sys tolic over least diastolic pressure of uterine or umbilical artery ass essed by the Doppler technique was closely correlated with the levels of maternal serum proteases in preeclampsia, which suggested that plac ental proteases might control uteroplacental circulation via the regul ation of concentrations of vasoactive peptides in uteroplacental circu lation. The degradation of immunomodulating peptides by placental prot ease also suggests the possible involvement of placental protease in t he immunological aspect of pregnancy.