Introduction:
Angioedema is a known adverse effect of renin-angiotensin-aldosterone system blockers.
It is characterized by non-inflammatory swelling of the head and neck region, and
increased plasma and tissue levels of bradykinin (BK). In-depth elucidation of bradykinin-dependent
mechanisms of microvascular destabilization are still needed to comprehend the molecular
pathways causing angioedema and for rational design of anti-edematous therapy. Therefore,
BK-induced changes in endothelial permeability and cellular architecture were investigated
in a model of human dermis microvasculature (HDMECs).
Methods:
Macromolecular tracer assays were used to examine BK-induced permeability changes
in primary HDMECs. BK-induced modulation of cell-to-cell junctional proteins expression
were investigated by western blot, qRT-PCR and microscopy. BK receptor 2 down-stream
signalling was investigated by calcium imaging and cGMP/cAMP ELISA. Finally, vascular
hyperpermeability target genes were determined by qRT-PCR.
Results:
It was found that BK acute stimulation increases HDMECs permeability to macromolecules,
results in down-regulation of claudin 5 expression and increment of phosphorylated
VE-Cadherin pool. These effects were diminished in presence of BK 2 receptor antagonist,
HOE 140. Release of intracellular calcium initiates down-stream signalling cascade,
which further results in up-regulation of Ang-2 and VEGF expression.
Conclusion:
BK acute stimulation alters the endothelial barrier function, increasing the permeability
to macromolecules and affecting the stability of cellular tight- and adherens- junctions.
Furthermore, it results in up-regulation of angiopoietins and vascular endothelial
growth factors expression thus promoting vascular homeostasis destabilization.
