INHIBITION OF CHEMOTACTIC MOTILITY AND TRANS-ENDOTHELIAL MIGRATION OFHUMAN NEUTROPHILS BY SPHINGOSINE 1-PHOSPHATE

In previous studies, we reported that sphingosine 1-phosphate (Sph-1-P ) inhibits the chemotactic motility of some cancer cell lines such as mouse melanoma cells, as well as human smooth muscle cells, at a very low concentration, as demonstrated by a transwell migration assay meth od (Proc, Natl. Acad, Sci. USA 89, 9698, 1992; J, Cell Biol, 130, 193, 1995), In this study, we investigated the effect of Sph-1-P on the ch emotactic motility and invasiveness of human neutrophils, utilizing th ree different assay systems: (a) a transwell migration assay where IL- 8 or fLMP was added as a chemotactic factor, (b) a phagokinetic assay with gold colloids, and (c) a trans-endothelial migration assay with h uman umbilical vein endothelial cells (HUVECs) plated on collagen laye rs, We found that among various sphingosine derivatives, Sph-1-P speci fically inhibited the IL-8- or fLMP-induced chemotactic migration of n eutrophils at concentrations below 1 mu M. Phagokinetic activity of ne utrophils was also suppressed by Sph-1-P, but more moderately than by the PKC inhibitory sphingosine analog, trimethylsphingosine. Finally, Sph-1-P inhibited trans-endothelial migration and invasiveness of neut rophils into HUVEC-covered collagen layers, whereas no effect on their adhesion to HUVECs was observed, These observations strongly suggest that Sph-1-P can act as a specific and effective motility regulator of human neutrophils, raising the possibility of future applications of Sph-1-P, or its analogs, as anti-inflammatory agents regulating invasi ve migration of neutrophils through endothelial layers at injured vasc ular sites. (C) 1997 Federation of European Biochemical Societies.