Extracellular vesicles from preeclampsia disrupt the blood-brain barrier via reduced claudin-5: potential role of vascular endothelial growth factor

Background Physiopathology of life-treating cerebrovascular complications in preeclampsia are yet unknown. We investigated whether disruption of the blood-brain barrier (BBB), generated using circulating small extracellular vesicles (sEVs) from women with preeclampsia or placentae cultured under hypoxic conditions, impairs the expression of tight junction proteins, such as claudin 5 (CLDN5), mediated by VEGF and activation of VEGF receptor 2 (KDR). Methods sEVs were isolated from plasma (normal pregnancy, sEVs-NP, n=9); preeclampsia, sEVs-PE, n=9) or placental explants from normotensive pregnancies, cultured in normoxia (sEVs-Nor, n=10) or hypoxia (sEVs-Hyp, n=10). The integrity of the BBB was evaluated using in vitro (human and mice brain endothelial cell lines) and in vivo (non-pregnant C57BL/6 mice (4 to 5 months old, (n=10) were injected with sEVs-Hyp), models. Results sEVs-PE and sEVs-Hyp reduced CLND5 levels (p<0.05) in the endothelial cell membrane without affecting other tight junction proteins. These results were negated with sEVs-PE sonication. sEVs-Hyp injected into non-pregnant mice generated neurological deficits and BBB disruption, specifically in the posterior area of the brain, associated with reduction in CLND5 levels in the brain cortex. Furthermore, sEVs-PE and sEVs-sHyp had higher VEGF levels than sEVs-NP and sEVs-Nor, respectively. Human brain endothelial cells exposed to sEVs-PE or sEVs-sHyp exhibited a reduction in the activation of KDR. Conclusion sEVs from hypoxic placentae and plasma from women with preeclampsia disrupt the BBB, via reduction of CLDN5, a phenomenon that may involve VEGF contained within these vesicles. These findings will improve the elucidation of cerebrovascular alterations in women with preeclampsia.