RESUMEN
After an acute phase of inflammation or injury, restoration of the endothelial barrier is important to regain vascular integrity and to prevent edema formation. However, little is known about mediators that control restoration of endothelial barrier function. We show here that oxidized phospholipids that accumulate at sites of inflammation and tissue damage are potent regulators of endothelial barrier function. Oxygenated epoxyisoprostane-containing phospholipids, but not fragmented oxidized phospholipids, exhibited barrier-protective effects mediated by small GTPases Cdc42 and Rac and their cytoskeletal, focal adhesion, and adherens junction effector proteins. Oxidized phospholipid-induced cytoskeletal rearrangements resulted in a unique peripheral actin rim formation, which was mimicked by coexpression of constitutively active Cdc42 and Rac, and abolished by coexpression of dominant-negative Rac and Cdc42. Thus, oxidative modification of phospholipids during inflammation leads to the formation of novel regulators that may be critically involved in restoration of vascular barrier function.
Asunto(s)
Endotelio Vascular/fisiología , Fosfatidilcolinas/farmacología , Esfingosina/análogos & derivados , Proteína de Unión al GTP cdc42/fisiología , Proteínas de Unión al GTP rac/fisiología , Hidroxitolueno Butilado/farmacología , Citoesqueleto/efectos de los fármacos , Citoesqueleto/ultraestructura , ADN Complementario/genética , Dimiristoilfosfatidilcolina/farmacología , Impedancia Eléctrica , Células Endoteliales/efectos de los fármacos , Células Endoteliales/fisiología , Endotelio Vascular/citología , Endotelio Vascular/efectos de los fármacos , Humanos , Isoprostanos/aislamiento & purificación , Isoprostanos/farmacología , Lisofosfolípidos/farmacología , Oxidación-Reducción , Fosfatidilcolinas/aislamiento & purificación , Arteria Pulmonar/citología , ARN Interferente Pequeño/farmacología , Espectrometría de Masa por Ionización de Electrospray , Esfingosina/farmacología , Relación Estructura-Actividad , Trombina/farmacología , Transfección , Proteína de Unión al GTP cdc42/genética , Proteínas de Unión al GTP rac/genética , Proteínas de Unión al GTP rho/metabolismoRESUMEN
BACKGROUND: Lecithin has been widely sold as a dietary supplement. 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) is a phospholipid that does not exist in nature and has been used in vitro to study lipid binding. We tested DMPC in vivo in apolipoprotein (apo) E-null mice. METHODS AND RESULTS: DMPC or soy or egg lecithin at 1.0 mg/mL was added to the drinking water of 4-week-old apoE-null female mice. Eight weeks later, HDL cholesterol levels and apoA-I levels were markedly increased in the mice that received DMPC. HDL function was also dramatically improved in the mice receiving DMPC, and there was a significant reduction in aortic lesions (P=0.021) in the DMPC mice but not in those receiving lecithin. Adding 1.0 mg/mL of DMPC to the drinking water of 10-month-old apoE-null female mice for 5 weeks caused regression of aortic sinus lesions (P=0.003). Adding 1.0 mg/mL DMPC to the drinking water of 6-month-old apoE-null male mice for 8 weeks significantly reduced aortic sinus lesion area (P=0.0031) and en face whole aorta lesion area (P=0.001), whereas adding the same concentrations of soy or egg lecithin did not significantly alter lesion area. Jejunal apoA-I synthesis and plasma apoA-I levels were increased 2- to 3-fold in mice receiving DMPC but not soy or egg lecithin. CONCLUSIONS: DMPC (but not lecithin) raises HDL cholesterol and apoA-I, improves HDL function, and prevents lesions or causes their regression in apoE-null mice.