Inhibition of plasma-mediated adherence of sickle erythrocytes to microvascular endothelium by conformationally constrained RGD-containing peptides
✍ Scribed by Kumar, Anjali; Eckman, James R.; Wick, Timothy M.
- Publisher
- John Wiley and Sons
- Year
- 1996
- Tongue
- English
- Weight
- 646 KB
- Volume
- 53
- Category
- Article
- ISSN
- 0361-8609
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✦ Synopsis
Adherence of sickle erythrocytes to vascular endothelium likely initiates or participates in microvascular occlusion, leading to ischemic tissue and organ damage characteristic of sickle-cell pain episodes. In vitro, sickle-cell adherence to endothelium involves adhesive plasma proteins and integrin and nonintegrin receptors on sickle cells and endothelial cells. The involvement of arginine-glycine-aspartic acid (RGD) sequences in adhesive plasma proteins and integrin receptors suggests that RGD-containing peptides may inhibit sickle-cell/endothelial-cell adherence. In the present study, inhibition of plasma-mediated sickle-erythrocyte adherence to endothelium using conformationally constrained RGDcontaining peptides was quantified in vitro under continuous flow at a shear stress of 1.0 dyn/cm2. Two conformationally constrained RGD peptides were investigated: 62 (which has high affinity for a&, a&, and alIlbP3 integrin receptors), and TP9201 (which preferentially binds to (~11&3). Peptide 62 at 50 pM inhibited plasma-mediated sickle-cell adherence to microvascular endothelium 70% when incubated with sickle red cells, and 63% when incubated with endothelium. Under similar conditions, peptide TP9201 inhibited plasmamediated sickle-cell adherence up to 85% at concentrations from 250 to 500 pM TP9201. The inhibition of plasma-mediated adherence by conformationally constrained RGD peptides, but not by linear or circular constructs, suggests that the tertiary structure of the peptide containing the binding sequence is important. Inhibition of plasma-mediated sickle-cell adhesion with these peptides in vitro suggests that such conformationally constrained RGD peptides could provide therapeutic interventions in the course of the disease by inhibiting receptor-ligand interactions.