Endothelial targeting and enhanced antiinflammatory effects of complement inhibitors possessing sialyl Lewis(x) moieties

The complement inhibitor soluble complement receptor type 1 (sCR1) and a tr uncated form of sCR1, sCR1[desLHR-A], have been generated with expression o f the selectin-reactive oligosaccharide moiety, sialyl Lewis(x) (sLe(x)), a s N-linked oligosaccharide adducts, These modified proteins, sCR1sLe(x) and sCR1[desLHR-A]sLe(x), were assessed in the L-selectin and P-selectin depen dent rat model of lung injury following systemic activation of complement b y cobra venom factor and in the L-selectin. P-selectin-, and E-selectin-dep endent model of lung injury following intrapulmonary deposition of IgG immu ne complexes, In the cobra venom factor model, sCR1sLe(x) and sCR1[desLHR-A ]sLe(x) caused substantially greater reductions in neutrophil accumulation and in albumin extravasation in lung when compared with the non-sLe(x)-deco rated forms. In this model, increased lung vascular binding of sCR1sLe(x) a nd sCR1[desLHR-A]sLe(x) occurred in a P-selectin-dependent manner, in contr ast to the absence of any increased binding of sCR1 of sCR1[desLHR-A]. In t he IgG immune complex model, sCR1[desLHR-A]sLe(x) possessed greater protect ive effects relative to sCR1[desLHR-A], based on albumin extravasation and neutrophil accumulation. Enhanced protective effects correlated Kith greate r lung vascular binding of sCR1[desLHR-A]sLe(x) as compared with the non-sL e(x)-decorated farm. In TNF-alpha-activated HUVEC, substantial in vitro bin ding occurred with sCR1[desLHR-A]sLe(x) (but not with sCR1[desLHR-A]), This endothelial cell binding was blocked by anti-E-selectin but not by anti-P- selectin. These data suggest that sLe(x)-decorated complement inhibitors ha ve enhanced antiinflammatory effects and appear to have enhanced ability to localize to the activated vascular endothelium.