Leukotriene B 4 mediates vascular smooth muscle cell migration through αvβ3 integrin transactivation

Abstract

Vascular injury leads to a local inflammatory response, characterized by endothelial damage, extracellular matrix exposition and aggregation/adhesion of platelets and circulating leukocytes. The release of inflammatory mediators amplifies the process, and can induce vascular smooth muscle cells (SMC) migration and proliferation. Released by leukocytes, leukotriene B 4 (LTB 4) induces reactive oxygen species production and SMC chemotaxis. This study was conducted to elucidate the molecular mechanisms involved in the effect of LTB 4 on SMC migration, and a rat linage of vascular SMC (A7r5) were used throughout. The chemotactic effect of LTB 4 was dependent on the concentration used, being comparable to AngII at 100 nM. Migration induced by LTB 4 was inhibited in the presence of pertussis toxin, CP-105696, a BLT1 receptor antagonist, and by LY294002 or PD98059, two inhibitors of PI3K and MEK1/2, respectively. Stimulation of SMC with LTB 4 triggered integrin-associated signaling pathways, inducing focal adhesion kinase (FAK) phosphorylation, mobilization of actin cytoskeleton, association of FAK to PI3K, ERK-2 phosphorylation and nuclear translocation, and also NFκB pathway activation. Pretreatment of SMC with a selective ligand of αvβ3 integrin, kistrin, inhibited LTB 4-induced chemotaxis, FAK phosphorylation, FAK-PI3K association, and also inhibited ERK-2 and NFκB pathways activation. Taken together, the data demonstrated, for the first time, that the effect of LTB 4 on SMC migration is modulated by integrin signaling activation, suggesting that these adhesion molecules might be important target for therapeutic intervention in cardiovascular diseases.