Renin-like immunoreactivity in uterus and placenta from normotensive and hypertensive pregnancies

Objectives. (1) To identify the distribution of renin-like immunoreactivity in placental bed, placenta-free uterine wall, placenta, fetal membranes, a nd intertwin membranes obtained from normal pregnancies and (2) to compare the findings in normal pregnancies with those in pregnancies complicated by various hypertensive disorders. Study design. Biopsies were taken from 31 normotensive pregnant women, eigh t of whom had twin pregnancies, and from 28 women with various hypertensive disorders of pregnancy. The anti-human renal renin monoclonal antibody, F3 7.1A1, was used for immunostaining. Histological structures were identified with standard H&E and PAS techniques, supplemented with immunostaining usi ng the specific cell markers CD68 and cytokeratin. Results. Renin-like immunoreactivity was found in cytokeratin immunolabelle d placental syncytiotrophoblast, amnionic and glandular epithelium, but mos t consistently in CD68 immunolabelled maternal and fetal macrophages. The d istribution of renin-like immunoreactivity throughout the pregnant uterus r oughly parallelled reported renin concentrations in the various tissues, wh ile its localization conforms also with that of cathepsin D. There were no obvious differences in renin-like immunolabelling between normotensive or h ypertensive women. Renin-like immunoreactivity was particularly common in t he atherotic lesions that are observed more often in pregnancies complicate d with hypertensive disorders of pregnancy and/or intra-uterine growth rest riction. Conclusions. The data complement earlier findings showing that only two of four anti-renal renin monoclonal antibodies, both of which cross-react with cathepsin D, give a positive immunostaining in placental tissue. They ques tion whether classical concepts on renin localisation in uteroplacental tis sues all relate to one and the same enzyme. The demonstration of renin-like enzymes in different cell types, including macrophages, may explain the di versity of functions that has been attributed to uterine renin. There were no differences between tissues obtained from normotensive and hypertensive pregnancies, except for the consistent presence of renin-like immunoreactiv ity in atherotic lesions. (C) 1998 Elsevier Science Ireland Ltd. All rights reserved.