Background
Bradykinin (BK) induces angiogenesis by promoting vessel permeability, growth and remodeling. This study aimed to demonstrate that the B2R antagonist, fasitibant, inhibits the BK pro-angiogenic effects. Methodology: We assesed the ability of fasibitant to antagonize the BK stimulation of cultured human cells (HUVEC) and circulating pro-angiogenic cells (PACs), in producing cell permeability (paracellular flux), migration and pseocapillary formation. The latter parameter was studied in vitro (matrigel assay) and in vivo in mice (matrigel plug) and in rat model of experimental osteoarthritis (OA). We also evaluated NF-κB activation in cultured cells by measuring its nuclear translocation and its downstream effectors such as the proangiogenic ciclooxygenase-2 (COX-2), prostaglandin E-2 and vascular endothelial growth factor (VEGF). Principal findings: HUVEC, exposed to BK (1-10 µM), showed increased permeability, disassembly of adherens and tight-junction, increased cell migration, and pseudocapillaries formation. We observed a significant increase of vessel density in the matrigel assay in mice and in rats OA model. Importantly, B2R stimulation elicited, both in HUVEC and PACs, NF-κB activation, leading to COX-2 overexpression, enhanced prostaglandin E-2 production. and VEGF output. The BK/NF-κB axis, and the ensuing amplification of inflammatory/angiogenic responses were fully prevented by fasitibant as well as by IKK VII, an NF-κB. Inhibitor.
Conclusion
This work illustrates the role of the endothelium in the inflammation provoked by the BK/NF-κB axis. It also demonstates that B2R blockade by the antaogonist fasibitant, abolishes both the initial stimulus and its amplification, strongly attenuating the propagation of inflammation.