RESUMEN
Leukostasis and tissue infiltration by leukemic cells are poorly understood life-threatening complications of acute leukemia. This study has tested the hypothesis that adhesion receptors and cytokines secreted by blast cells play central roles in these reactions. Immunophenotypic studies showed that acute myeloid leukemia (AML) cells (n = 78) of the M0 to M5 subtypes of the French-American-British Cooperative Group expressed various amounts of adhesion receptors, including CD11a, b, c/CD18, CD49d, e, f/CD29, CD54, sCD15, and L-selectin. The presence of functional adhesion receptors was evaluated using a nonstatic adhesion assay. The number of blast cells attached to unactivated endothelium increased by 7 to 31 times after a 6-hour exposure of endothelium to tumor necrosis factor (TNF)-alpha. Inhibition studies showed that multiple adhesion receptors--including L-selectin, E-selectin, VCAM-1, and CD11/CD18--were involved in blast cell adhesion to TNF-alpha-activated endothelium. Leukemic cells were then cocultured at 37 degrees C on unactivated endothelial cell monolayers for time periods up to 24 hours. A time-dependent increase in the number of blasts attached to the endothelium and a concomitant induction of ICAM-1, VCAM-1, and E-selectin were observed. Additional experiments revealed that endothelial cell activation by leukemic myeloblasts was caused by cytokine secretion by blast cells, in particular TNF-alpha and IL-1 beta, and direct contacts between adhesion receptors expressed by blast cells and endothelial cells. Thus, leukemic cells have the ability to generate conditions that promote their own adhesion to vascular endothelium, a property that may have important implications for the pathophysiology of leukostasis and tissue infiltration by leukemic blast cells. (Blood. 2001;97:2121-2129)
Asunto(s)
Antígenos CD/biosíntesis , Moléculas de Adhesión Celular/biosíntesis , Endotelio Vascular/metabolismo , Regulación Leucémica de la Expresión Génica , Interleucina-1/metabolismo , Leucemia Mieloide/patología , Infiltración Leucémica/metabolismo , Leucostasis/metabolismo , Proteínas de Neoplasias/metabolismo , Células Madre Neoplásicas/metabolismo , Factor de Necrosis Tumoral alfa/metabolismo , Antígenos CD/genética , Antígenos CD18/biosíntesis , Antígenos CD18/genética , Adhesión Celular , Moléculas de Adhesión Celular/genética , Células Cultivadas , Técnicas de Cocultivo , Selectina E/biosíntesis , Selectina E/genética , Endotelio Vascular/patología , Humanos , Integrina alfa4 , Integrina alfa5 , Integrina alfa6 , Integrina alfaXbeta2/biosíntesis , Integrina alfaXbeta2/genética , Integrina beta1/biosíntesis , Integrina beta1/genética , Molécula 1 de Adhesión Intercelular/biosíntesis , Molécula 1 de Adhesión Intercelular/genética , Selectina L/biosíntesis , Selectina L/genética , Leucemia Mieloide/genética , Leucemia Mieloide/metabolismo , Infiltración Leucémica/genética , Leucostasis/genética , Antígeno Lewis X/biosíntesis , Antígeno Lewis X/genética , Antígeno-1 Asociado a Función de Linfocito/biosíntesis , Antígeno-1 Asociado a Función de Linfocito/genética , Antígeno de Macrófago-1/biosíntesis , Antígeno de Macrófago-1/genética , Proteínas de Neoplasias/biosíntesis , Proteínas de Neoplasias/genética , Células Madre Neoplásicas/citología , Receptores Mensajeros de Linfocitos/biosíntesis , Receptores Mensajeros de Linfocitos/genética , Células Tumorales Cultivadas , Molécula 1 de Adhesión Celular Vascular/biosíntesis , Molécula 1 de Adhesión Celular Vascular/genéticaRESUMEN
Selectins play a major role in the inflammatory reaction by initiating neutrophil attachment to activated vascular endothelium. Some heparin preparations can interact with L- and P-selectin; however, the determinants required for inhibiting selectin-mediated cell adhesion have not yet been characterized. We now report that carboxyl-reduced and sulfated heparin (prepared by chemical modifications of porcine intestinal mucosal heparin leading to the replacement of carboxylates by O-sulfate groups) and trestatin A sulfate (obtained by sulfation of trestatin A, a non-uronic pseudo-nonasaccharide extracted from Streptomyces dimorphogenes) exhibit strong anti-P-selectin and anti-L-selectin activity while lacking antithrombin-mediated anticoagulant activity. In vitro experiments revealed that both compounds inhibited P-selectin- and L-selectin-mediated cell adhesion under laminar flow conditions. Moreover, carboxyl-reduced and sulfated heparin and trestatin A sulfate were also active in vivo, as assessed by experiments showing 1) that microinfusion of trestatin A sulfate reduced by 96% leukocyte rolling along rat mesenteric postcapillary venules and 2) that both compounds inhibited (by 58-81%) neutrophil migration into thioglycollate-inflamed peritoneum of BALB/c mice. These results indicate that nonanticoagulant sulfated saccharides targeted at P-selectin and L-selectin may have therapeutic potential in inflammatory disorders.
