Upregulation of cytokeratins in the extravillous trophoblast in the basal plate of healthy and pre-eclamptic placentae

This research has determined which specific keratin molecular species are upregulated when comparing the chorionic villous trophoblast (CVT) to the extravillous trophoblast (EVT) in the basal plate tissues of placentae from healthy and pre-eclamptic mothers at term. Indirect immunofluorescence Confocal Laser Scanning Microscopy (CLSM) revealed that at least 5 keratin proteins are expressed in villous trophoblast and the same 5 in extravillous trophoblast. A further 15 keratin proteins tested were undetectable in these tissues. All the specific keratins identified (K5, 7, 8, 18 and 19) in trophoblast were upregulated by over 20-fold in the EVT “percentage of pixels with high intensity”, a reflection of increased specific immunofluorescence. The statistically significant difference (P < 0.0001) of K5 for example, showed an increase from a median pixel value of 0.14% in CVT to 2.88% in the EVT whereas in the pre-eclamptic there was an increase from 0.06% in the CVT to 2.97% in the EVT. Similar patterns were obtained for K7, 8, 18, and 19. The reduction in the ratio of 4.8:1 of the percentage median pixel intensity from the healthy to pre-eclamptic CVT keratin related immunofluorescence expression was statistically significant in all 5 keratins (p < 0.0001). There were no significant differences in immunofluorescence pixel intensity for the EVTs at the CLSM level. At the electron microscopy level, immunogold labelling technique using anti-K7 and anti-K18 antibodies which were representatives of the two major keratin families TYPE II and TYPE I respectively, were down regulated in the CVT and EVT in pre-eclamptic compared with the healthy. On the basis of the results of these investigations the villous trophoblast in pre-eclamptic placentae may be cytoskeletally weaker through deficiency of these keratin filaments. This could be a reason why, in pre-eclampsia, trophoblast is deported in greater quantity than in healthy placenta.