Lipoxin A4 Mediates Aortic Contraction via RHOA/RHO Kinase, Endothelial Dysfunction and Reactive Oxygen Species

Background: Lipoxin A4 (LXA(4)) is a biologically active product generated from arachidonic acid by lipoxygenase action. The production of lipoxins is enhanced by aspirin through acetylation of cyclooxygenase-2, via a mechanism known as 'aspirin-triggered lipoxin'. LXA(4) has both anti-inflammatory and proinflammatory actions, the latter being related with reocclusion and restenosis after coronary angioplasty in patients treated with aspirin. However, little is known of the actions of LXA(4) on the vasculature. We hypothesized that LXA(4) promotes contractile responses and contributes to endothelial dysfunction. Methods: We used aorta from Wistar rats to assess vascular function. Reactive oxygen species (ROS) production and contractile and regulatory proteins were investigated. Results: LXA(4) induced concentration-dependent contractions via formyl peptide receptor-2 activation and both RhoA/Rho kinase inhibitor and ROS scavenger decreased this contraction. Also, endothelium removal, and COX-2 and NAD(P)H oxidase inhibitors attenuate the LXA(4)-induced contraction. LXA(4) potentiated phenylephrine-induced contraction and inhibited acetylcholine-induced relaxation. In the presence of LXA(4), ROS production was increased and protein expression of RhoA, phospho-myosin light chain, COX-2 and p67phox was higher. Conclusion: LXA(4) has a functional role in the vasculature and may contribute to further vascular damage in conditions where its production is exacerbated, such as in angioplasty-associated complications treated with aspirin. (C) 2015 S. Karger AG, Basel