Inhibition of L-selectin binding by polyacrylamide-based conjugates under defined flow conditions.
Selectins mediate tethering and rolling of leukocytes along the endothelium in a shear force-dependent manner. This key step in the cellular immune response is a target for experimental anti-inflammatory therapies. In the present paper we have examined the inhibitory activity of the minimal selectin ligand sialyl Lewis x (SiaLe(x)), its isomer sialyl Lewis a (SiaLe(a)) and sulfated tyrosine (sTyr) residues under dynamic flow reflecting the rheological conditions in the blood stream. The monomeric ligands were compared to multivalent polyacrylamide (PAA)-based conjugates under defined flow conditions on the molecular level, using surface plasmon resonance (SPR) technology, and on the cellular level, using a parallel-plate flow chamber. SPR measurements showed that a spatial arrangement of binding epitopes mimicking the selectin binding motif of the natural ligand PSGL-1 inhibits L-selectin binding successfully with IC(50) values in the nanomolar range. Using a flow chamber adhesion assay it could be shown that the multivalent inhibitors efficiently blocked rolling and tethering of NALM-6 pre-B cells transfected with human L-selectin to activated endothelium and that the inhibitory activity increased with rising shear stress. While PAA-conjugates were almost not inhibitory at low shear stress, NALM-6 cell rolling was nearly completely inhibited at high shear stress. The results indicate that multimeric conjugates of SiaLe(x), SiaLe(a) and sTyr are highly effective inhibitors of L-selectin-mediated cell adhesion particularly under flow conditions. Consequently, SiaLe(x), SiaLe(a) and/or sTyr on macromolecular carriers may be promising candidates for anti-inflammatory therapy.
Enders
Sven
S
Zentralinstitut für Laboratoriumsmedizin und Pathobiochemie, Charité - Universitätsmedizin, Berlin, Campus Benjamin Franklin, Hindenburgdamm 30, D-12200 Berlin, Germany.
Bernhard
Gesche
G
Zakrzewicz
Andreas
A
Tauber
Rudolf
R
D000180:Acrylic Resins; D015374:Biosensing Techniques; D018395:CA-19-9 Antigen; D004730:Endothelium, Vascular / Q000166:cytology / Q000378:metabolism; D005732:Gangliosides / Q000378:metabolism* / Q000494:pharmacology; D018056:Hemorheology; D006801:Humans; D019041:L-Selectin / Q000187:drug effects / Q000378:metabolism*; D000080506:Sialyl Lewis X Antigen; D020349:Surface Plasmon Resonance; D014443:Tyrosine / Q000031:analogs & derivatives / Q000378:metabolism / Q000494:pharmacology
D000180:Acrylic Resins; D018395:CA-19-9 Antigen; D005732:Gangliosides; D000080506:Sialyl Lewis X Antigen; C094688:sialyl Lewis(x) ganglioside; D019041:L-Selectin; C074962:poly-N-(2-hydroxyethyl)acrylamide; C005662:tyrosine O-sulfate; D014443:Tyrosine; C064564:sialyl Le(a) ganglioside