Neuronal Protection in Stroke by an sLe ^x -Glycosylated Complement Inhibitory Protein

Abstract

Glycoprotein adhesion receptors such as selectins contribute to tissue injury in stroke. Ischemic neurons strongly expressed C1q, which may target them for complement-mediated attack or C1qRp-mediated clearance. A hybrid molecule was used to simultaneously inhibit both complement activation and selectin-mediated adhesion. The extracellular domain of soluble complement receptor-1 (sCR1) was sialyl Lewis x glycosylated (sCR1sLex) to inhibit complement activation and endothelial-platelet-leukocyte interactions. sCR1 and sCR1sLex colocalized to ischemic cerebral microvessels and C1q-expressing neurons, inhibited neutrophil and platelet accumulation, and reduced cerebral infarct volumes. Additional benefit was conferred by sialyl Lewis x glycosylation of the unmodified parent sCR1 molecule.

Complement C1q Is Dramatically Up-Regulated in Brain Microglia in Response to Transient Global Cerebral Ischemia

“…These findings, however, are in contrast to recently published immunocytochemical data which were interpreted to indicate that C1q biosynthesis is absent in normal mouse brain and induced de novo and exclusively in neurons during reperfusion after transient focal cerebral ischemia in the mouse brain (40). Thus far, this conclusion has not been corroborated by in situ hybridization analysis.…”

“…It is conceivable that raised levels of C1q may promote inflammation in two ways: 1) they may lead to increased levels of functionally active C1 complexes, thus driving a local activation of the classical complement activation cascade (1); 2) they might trigger cellular responses by binding to C1q receptors (1,43). The potential benefits of using complement inhibitors as a novel therapeutic approach in the treatment of inflammatory and degenerative neurological diseases is highlighted by a recent report of Huang et al (40) which demonstrates a reduced cerebral infarct volume and neuronal protection by infusion of a hybrid molecule that simultaneously inhibits complement activation and selectin-mediated adhesion in a murine experimental model of focal cerebral ischemia in mice. These results, however, do not permit assessment of the contribution of enhanced C1q biosynthesis, because the complement-inhibitory activity of the hybrid molecule used in this study becomes effective further downstream of C1 activation only and may inhibit each of the three activation routes of complement.…”

sCR1sLeX reduces lung allograft ischemia–reperfusion injury but does not ameliorate acute rejection

“…A further advantage may be that sCR1sLe X accumulates in inflamed areas through binding to endothelial selectins [7]. In vivo models of experimental stroke [8], myocardial infarction [6] and neutrophil dependent acute lung injury [7] demonstrated that sCR1sLe X efficiently inhibited complement. In the stroke model the administration of sCR1sLe X at the time of reperfusion also improved outcome, albeit to a lesser degree.…”

“…sCR1sLe X reduced myocardial infarct size [6] and neutrophil infiltration in acute lung injury models in vivo [7] as well as infarct size and consecutive neurologic deficit in experimental stroke in mice. Its effect has been demonstrated not only when sCR1sLe X has been given as pretreatment, but also when the drug has been administered after the onset of ischemia [8]. In these models sCR1sLe X was superior to sCR1 in several aspects.…”

Engineered human soluble calcium-activated nucleotidase inhibits coagulation in vitro and thrombosis in vivo

“…Since platelet activation and aggregation occurs early in the process of the thrombosis, inhibition of platelet function has become a cornerstone of therapy to prevent thrombus formation [2]. ADP has long been recognized as a potent platelet agonist and component of platelet dense granules, which not only triggers aggregation but also augments the action of other platelet agonists [3,4].…”