Resistin up-regulates fractalkine expression in human endothelial cells: lack of additive effect with TNF-alpha.

Resistin is a cytokine and fractalkine (Fk) a cell adhesion molecule and chemokine that contribute to human vascular inflammation by mechanisms not clearly defined. We questioned whether resistin induces Fk expression in human endothelial cells (HEC), compared the effect with that of the pro-inflammatory cytokine, TNF-alpha, and evaluated the consequences of co-stimulating HEC with both activators on Fk induction and on the signalling molecules involved. We found that resistin up-regulated Fk expression at comparable level to that of TNF-alpha by a mechanism involving P38 and JNK MAPK and NF-kappaB. Co-stimulation of cells with resistin and TNF-alpha did not increase Fk expression induced by every single inducer. Moreover resistin reduced the expression induced by TNF-alpha in HEC. The new data uncover Fk as a novel molecular link between resistin and inflammation and show that resistin and TNF-alpha have no additive effect in Fk up-regulation or on the signalling molecules implicated.