Angiotensin III induces disruption of blood-brain barrier integrity in vitro in bEnd.3 brain endothelial cells

Abstract

Hypertension is well-known to cause disruption of the blood-brain barrier (BBB). Angiotensin (Ang) II is one of the major mechanistic factors leading to impairment of BBB integrity under hypertensive states. However, the impact of Ang III, produced by conversion from Ang II, on the BBB remains to be elucidated. Therefore, this study was aimed to evaluate the effect of Ang III on an in vitro model of BBB using mouse brain microvascular endothelial cell line (bEnd.3). Following exposure of bEnd.3 cells to Ang III at doses ranging between 10 and 1000 nM for 6, 12, and 24 h, cell viability, transendothelial electrical resistance (TEER), and permeability of sodium fluorescein (NaFl) tracer were determined. The expression of claudin-5, caveolin-1 (Cav-1) and major facilitator superfamily domain-containing protein 2a (Mfsd2a) were assessed using immunofluorescence and western blotting. Overall decreases in cell viability and TEER and increases in NaFl permeability were observed at all time points following Ang III administration at various doses (P < 0.05, P < 0.01). 12-h treatment of Ang III at 25, 50, and 500 nM doses decreased claudin-5 but increased Cav-1 expression, while Mfsd2a expression decreased significantly by 500 nm Ang III (P < 0.0001). Our data demonstrate for the first time that Ang III leads to alterations in transport of substances across the BBB through both paracellular and transcellular pathways when administered at specific concentrations and durations in in vitro setting which suggests that it may potentially play a role in the disruption of BBB integrity under hypertensive conditions. (Figure presented.)