DISEQUILIBRIUM BETWEEN AT1R AND B2R ALTERS THE STRUCTURE AND THE INVASIVE CAPACITY OF HUMAN DERIVED TROPHOBLASTS
Alberto Leguina-Ruzzi, Jenny Corthorn, Liliana Garmendia, Eduardo Machuca, Gloria Valdes
Escuela de Medicina Pontificia Universidad Católica, Santiago, Chile.
Preeclampsia (PE) is initiated by a defective extravillous trophoblast (EVT) invasion. The local renin-angiotensin system (RAS) is enhanced in PE; its counter-regulatory kallikrein–kinin system is present in EVTs. In adition, angiotensin II (AII) inhibits EVT invasion via the AT1R, while bradykinin stimulates migration and invasion via the B2R. We postulate that submitting EVTs to AII stimulation and blockade of bradykinin B2R impairs trophoblast invasion. The aim of the present study was to evaluate the effect of a imbalance of the RAS and the kallikrein-kinin systems provoked by AII and B2R blockade by Bradyzide (BDZ) on the migratory phenotype and the invasive capacity of the validated EVT model of HRT8/SVneo cells. Immunoreactivity identified the receptor panel and MTS and Ki67 viability and proliferation. Filopodias were examined by phalloidin and invasion by the Transwell system. AT1, AT2, B1R and B2R were also identified by western blot. Cells were incubated 18 h with AII (10−7 M), BDZ (10−7 M) and losartan (5 × 10−5 M). Experiments were performed in duplicate ×3. Results are expressed as mean±SE; statistical analysis by one-way ANOVA and post-hoc tests. HTR-8/SVneo cells expressed LMWK, AT1, AT2, B1R and B2R. AII, AII+BDZ and losartan induced marked changes in filopodias (Figure 1). AII and AII+BDZ reduced the filopodias as compared to control (5.1±0.03 to 2.0±0.3 and 1.8±0.4 respectively; P<0.001). The invasion index decreased by BDZ and AII+BDZ from 1.0±0.0 to 0.6±0.1 and 0.3±0.5; P<0.05 and 0.001 respectively. Losartan reverted the effect of AII on the invasion index (0.7±0.0; P<0.001). This study demonstrates that disequilibrating AII/bradykinin alters the invasive capacity of HTR-8/SVneo cells. The reversal of the AII decreased invasion by losartan points to an AT1R effect. Further work is needed to validate these findings in EVT primary cultures and in animal models.
Keywords: Preeclampsia; Trophoblast Invasion; Angiotensin II; Bradykinin.