Sialyl Lewis(x) (sLe(x)) and an sLe(x) mimetic, CGP69669A, disrupt E- selectin-dependent leukocyte rolling in vivo

Leukocyte rolling is the earliest observable event in their recruitment from the circulation to inflamed tissue. This rolling is mediated largely by interaction between the selectin family of adhesion molecules and their glycosylated ligands. Although the nature of these ligands and their interaction with the selectins is not fully understood, it is accepted that expression of fucosylated sialylated glycans such as sialyl Lewis(x) (sLe(x)) is required for function. Despite findings that sLe(x) inhibits binding of leukocytes to E-selectin in vitro, and has beneficial effects in inflammatory disease models, inhibition of E-selectin-dependent leukocyte rolling in vivo has not been described. Functional overlap between the selectins has been noted and reduction of rolling by E-selectin antibodies only occurs if P- selectin is absent or blocked. We demonstrate that leukocyte rolling velocity in tumor necrosis factor alpha (TNFα)-stimulated mouse cremaster is increased following treatment with either sLe(x) or the sLe(x)-mimetic CGP69669A and that rolling is dramatically reduced if CGP69669A is applied in the presence of anti-P-selectin antibody. These effects are characteristic of E-selectin antagonism. In contrast, surgically stimulated (L- or P-seLectin- dependent) rolling is unaffected by either sLe(x) or CGP69669A. Our data demonstrate that CGP69669A is an effective and selective antagonist of E- selectin in vivo.