Bioactivity of nitrolinoleate: effects on adhesion molecules and CD40–CD40L system

Abstract

The vascular effects of nitrolinoleate (LNO 2), an endogenous product of linoleic acid (LA) nitration by nitric oxide-derived species and a potential nitrosating agent, were investigated on rat endothelial-leukocyte interactions. Confocal microscopy analysis demonstrated that LNO 2 was capable to deliver free radical nitric oxide ( ·NO) into cells, 5 min after its administration to cultured cells, with a peak of liberation at 30 min. THP-1 monocytes incubated with LNO 2 for 5 min presented nitrosation of CD40, leading to its inactivation. Other anti-inflammatory actions of LNO 2 were observed in vivo by intravital microscopy assays. LNO 2 decreased the number of adhered leukocytes in postcapillary venules of the mesentery network. In addition to this, LNO 2 reduced mRNA and protein expression of β2-integrin in circulating leukocytes, as well as VCAM-1 in endothelial cells isolated from postcapillary venules, confirming its antiadhesive effects on both cell types. Moreover, 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide, a nitric oxide scavenger, partially abolished the inhibitory action of LNO 2 on leukocyte-endothelium interaction, suggesting that the antiadhesion effects of LNO 2 involve a dual role in leukocyte adhesion, acting as a nitric oxide donor as well as through nitric oxide-independent mechanisms. In conclusion, LNO 2 inhibited adhesion molecules expression and promoted ·NO inactivation of the CD40–CD40L system, both important processes of the inflammatory response.