Atherosclerosis 212 (2010) 406–413 Contents lists available at ScienceDirect Atherosclerosis journal homepage: www.elsevier.com/locate/atherosclerosis Leukotriene B 4 mediates vascular smooth muscle cell migration through v3 integrin transactivation João Moraes a , Jamil Assreuy b , Cláudio Canetti c , Christina Barja-Fidalgo a,∗ a Departamento de Farmacologia, Universidade do Estado do Rio de Janeiro, UERJ, Rio de Janeiro, RJ, Brazil b Departamento de Farmacologia, Universidade Federal de Santa Catarina, UFSC, Florianópolis, SC, Brazil c Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, UFRJ, Rio de Janeiro, RJ, Brazil article info Article history: Received 21 February 2010 Received in revised form 17 May 2010 Accepted 6 June 2010 Available online 11 June 2010 Keywords: LTB4 SMC FAK PI3K v3 integrin 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 inflam- matory 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 produc- tion 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, respec- tively. 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 NFB pathway activation. Pretreatment of SMC with a selective ligand of v3 integrin, kistrin, inhibited LTB 4 -induced chemotaxis, FAK phospho- rylation, FAK-PI3K association, and also inhibited ERK-2 and NFB 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. © 2010 Elsevier Ireland Ltd. All rights reserved. 1. Introduction Inflammation is a classical feature observed in vascular injuries, usually characterized by endothelial damage, extracellular matrix exposure, and aggregation/adhesion of platelets and leukocytes [1]. The release of inflammatory mediators amplifies this process and induces vascular smooth muscle cells (SMC) migration and prolif- eration [2], what can lead to neointimal hyperplasia. Importantly, SMC recruitment is observed in vascular diseases associated with high mortality, such as atherosclerosis and restenosis. Leukotriene B 4 (LTB 4 ) is a lipid derivative of the arachidonic acid pathway generated by 5-lipoxygenase (5-LO) and leukotriene A 4 hydrolase, produced during several chronic inflammatory condi- tions, including atherosclerosis. 5-LO is highly expressed within ∗ Corresponding author at: Departamento de Farmacologia, Instituto de Biolo- gia Roberto Alcântara Gomes, Universidade do Estado do Rio de Janeiro, Ave 28 de Setembro 87, fundos, 5 andar, CEP:20550-030, Brazil. Tel.: +55 21 2587 6398, fax: +55 21 2587 6808. E-mail address: barja-fidalgo@uerj.br (C. Barja-Fidalgo). human carotid, aortic, and coronary artery plaques and genetic studies have also associated particular variants of 5-LO and its accessory protein, 5-LO activating protein, with stroke and myocar- dial infarction in humans [3,4]. LTB 4 exerts its actions through the interactions with membrane-bound G protein-coupled receptors (BLT1 and BLT2) [5]. Recent studies demonstrated that BLT1- deficient mice did not develop atherosclerosis, showing the pivotal involvement of LTB 4 in this disease [6]. Furthermore, it has also been demonstrated that LTB 4 induces reactive oxygen species (ROS) formation [7] and also acts as chemotactic agent for SMC in cytokine primed cells [6,8]. It is well known that integrins expression by SMC is a crucial step during the migration process [9]. Integrins are heterodimeric mem- brane glycoproteins that build up more than 30 distinct receptors. One type of receptor involved in SMC adhesion to fibronectin and collagen is 51 integrin [10,11], while v3 integrin mediates the interaction with vitronectin and osteopontin, two molecules related to SMC migration and proliferation [11]. Interestingly, v3 integrin expression is upregulated in media and adventitia during hyperplastic responses in injured arteries [12]. Different studies showed that v3 integrin blockage by antibodies or selective pep- 0021-9150/$ – see front matter © 2010 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.atherosclerosis.2010.06.009