Regulation of human feto-placental endothelial barrier integrity by vascular endothelial growth factors: competitive interplay between VEGF-A165a, VEGF-A165b, PIGF and VE-cadherin.

This study investigated the interplay of these factors on junctional occupancy of VE-cadherin and macromolecular leakage in human endothelial monolayers and the perfused placental microvascular bed.  Whilst VEGF-A165a (50 ng/ml) increased endothelial monolayer albumin permeability (p<0.0001), equimolar concentrations of VEGF-A165b (p>0.05) or PlGF (p>0.05) did not. Moreover, VEGF-A165b (100 ng/ml; p<0.001) but not PlGF (100 ng/ml; p>0.05) inhibited VEGF-A165a-induced permeability when added singly. PlGF abolished the VEGF-A165b-induced reduction of VEGF-A165a mediated permeability (p>0.05); PlGF was found to compete with VEGF-A165b for binding to Flt-1 at equimolar affinity. Junctional occupancy of VE-cadherin matched alterations in permeability. In the perfused microvascular bed, VEGF-A165b did not induce microvascular leakage but inhibited and reversed VEGF-A165a-induced loss of junctional VE-cadherin and tracer leakage. These results indicate that the anti-angiogenic VEGF-A165b isoform does not increase permeability in human placental microvessels or HUVEC primary cells and can interrupt VEGF-A165a-induced permeability. Moreover, the interplay of these isoforms with PIGF (and s-flt1) suggests that the ratio of these three factors may be important in determining the placental and endothelial barrier in normal and complicated pregnancies.
Source: Clinical Science - Category: Biomedical Science Authors: Tags: PublishAheadOfPrint Source Type: research