Effect of recombinant soluble P-selectin glycoprotein ligand-1 on leukocyte-endothelium interaction in vivo. Role in rat traumatic shock.

-Traumatic shock induces profound pathophysiological alterations and initiates inflammatory reactions in many tissues, thus resulting in acute multiple organ damage (eg, intestine, pancreas, and liver). In the rat, Noble-Collip drum trauma increases P-selectin expression on the vascular endothelium as a result of loss of endothelium-derived NO. Here we postulated that blockade of the earliest steps in leukocyte adhesion (ie, leukocyte rolling) via administration of a recombinant soluble form of P-selectin glycoprotein ligand-1 (PSGL-1; the recombinant soluble form is rsPSGL.Ig) would attenuate selectin-mediated events observed in the rat during traumatic shock. Using intravital microscopy of the rat mesenteric microvasculature, we found that intravenous infusion of rsPSGL.Ig significantly inhibited leukocyte-endothelium interaction (ie, leukocyte rolling, adherence, and transmigration) induced by traumatic shock as well as by activation of the microvascular endothelium with 50 micromol/L NG-nitro-L-arginine methyl ester. Immunohistochemical detection of P-selectin on the mesenteric venular endothelial surface demonstrated that rsPSGL.Ig functionally neutralizes effects of P-selectin on the endothelial cell surface rather than attenuating P-selectin expression. Systemic administration of rsPSGL.Ig to traumatized rats prolonged survival time and survival rate, significantly attenuating ileal myeloperoxidase activity and significantly preserving mesenteric endothelial function. Furthermore, PSGL-1 mRNA levels were significantly increased in the blood of traumatized rats and were reduced after systemic administration of rsPSGL.Ig. Thus, soluble recombinant forms of PSGL-1 are able to ameliorate acute shock states by suppressing selectin-mediated leukocyte-endothelium interaction at both the functional and molecular levels.