Expression of inhibin/activin subunits alpha (-αa), betaA (-βA) and betaB (-βB) in placental tissue of normal, preeclamptic and HELLP pregnancies

Aims were (a) the determination of the frequency and tissue distribution of the inhibin/activin (INH) subunits in human placental tissue of normal and preeclamptic/HELLP pregnancies and (b) the assessment of a combined expression of INH-α and both β-subunits (βA-and βB) using immunofluorescence technique. A significant lower expression of INH-α in preeclamptic and HELLP extravillous trophoblast cells compared to normal pregnancies was observed, while the INH-α immunostaining was significantly upregulated in syncytotropoblast. This lower expression suggests a higher production of activins rather than inhibins in preeclampsia and HELLP. Additionally, a significant down-regulation of INH-βB in extravillous trophoblast cells between normal and HELLP placental tissue was demonstrated, while INH-βA was significantly higher in preeclamptic syncytotrophoblast cells. The lower INH-βB expression suggests that this subunit might have an important role in the pathogenesis of HELLP syndrome. We also showed a colocalisation of INH-α and the INH-βA/-βB, suggesting a production and secretion of intact inhibin (A and B). Additionally, the higher expression of the INH-βA suggest a higher production of activin A and inhibin A in preeclampsia and might be utilized as a marker of placental function.