A novel lysophosphatidic acid analog, LXR-1035, inhibits leukocyte-endothelium interaction via inhibition of cell adhesion molecules.

A novel synthetic phosphorothioate analog of oleoyl lysophosphatidic acid LXR-1035 was studied for its ability to modulate leukocyte-endothelial cell interactions using intravital microscopy of the rat mesentery. Superfusion of the rat mesentery with 50 microM L-NAME elicited a significant, time-dependent increase in leukocyte rolling, adherence, and transmigration compared to control rats superfused with Krebs-Henseleit solution. However, superfusion of the rat mesentery with 300 nM LXR-1035 consistently attenuated 65-87% of the L-NAME-induced leukocyte rolling, adherence, and transmigration, without altering systemic blood pressure or mesenteric venular shear rate. Similar results were also obtained in rats subjected to 90 min of hemorrhage followed by 90 min of reperfusion. Resuscitation from hemorrhage increased significantly the number of rolling, adherent, and transmigrated leukocytes in the rat mesenteric microcirculation. However, superfusion of the rat mesentery with LXR-1035 markedly attenuated the leukocyte-endothelium interaction occurring after hemorrhage and reinfusion by 75+/-12%. Immunohistochemical localization of P-selectin expression on mesenteric venular endothelium was significantly increased after exposure to L-NAME and after hemorrhage-reinfusion, which was significantly attenuated by LXR-1035 (P<0.05). In addition, treatment of isolated rat neutrophils with 300 nM LXR-1035 significantly attenuated leukotriene B4-induced up-regulation of CD18 (P<0.05). Our data clearly demonstrate that LXR-1035 can potently inhibit the recruitment of leukocytes in the mesenteric rat microvasculature by attenuating cell-surface expression of adhesion molecules.