Peptides based on αV-binding domains of erythrocyte ICAM-4 inhibit sickle red cell-endothelial interactions and vaso-occlusion in the microcirculation

Abstract

Growing evidence shows that adhesion molecules on sickle erythrocytes interact with vascular endothelium leading to vaso-occlusion. Erythrocyte intercellular adhesion molecule-4 (ICAM-4) binds alphaV-integrins, including alphaVbeta3 on endothelial cells. To explore the contribution of ICAM-4 to vascular pathology of sickle cell disease, we tested the effects of synthetic peptides, V(16)PFWVRMS (FWV) and T(91)RWATSRI (ATSR), based on alphaV-binding domains of ICAM-4 and capable of inhibiting ICAM-4 and alphaV-binding in vitro. For these studies, we utilized an established ex vivo microvascular model system that enables intravital microscopy and quantitation of adhesion under shear flow. In this model, the use of platelet-activating factor, which causes endothelial oxidant generation and endothelial activation, mimicked physiological states known to occur in sickle cell disease. Infusion of sickle erythrocytes into platelet-activating factor-treated ex vivo rat mesocecum vasculature produced pronounced adhesion of erythrocytes; small-diameter venules were sites of maximal adhesion and frequent blockage. Both FWV and ATSR peptides markedly decreased adhesion, and no vessel blockage was observed with either of the peptides, resulting in improved hemodynamics. ATSR also inhibited adhesion in unactivated microvasculature. Although infused fluoresceinated ATSR colocalized with vascular endothelium, pretreatment with function-blocking antibody to alphaVbeta3-integrin markedly inhibited this interaction. Our data strengthen the thesis that ICAM-4 on sickle erythrocytes binds endothelium via alphaVbeta3 and that this interaction contributes to vaso-occlusion. Thus peptides or small molecule mimetics of ICAM-4 may have therapeutic potential.

Modulation of erythroid adhesion receptor expression by hydroxyurea in children with sickle cell disease

“…[7][8][9] More recently, two other molecules not restricted to reticulocytes have been implicated, namely Lutheran blood group/basal cell adhesion molecule (Lu/BCAM), a receptor for the extracellular matrix protein laminin α5 10,11 and intercellular adhesion molecule-4 (ICAM-4), otherwhise known as LW blood group glycoprotein, which binds different types of integrins, particularly αVβ3. [12][13][14] Other molecules may also increase the adhesiveness of sickle red cells. 6 On the endothelial side, the major cell membrane ligands for red blood cell adhesion molecules include vascular cell adhesion molecule-1 (VCAM-1), CD36, αVβ3 integrin and selectins, 4,5 but recently a new interaction that involves endothelial Lu/BCAM and α4β1 integrin on sickle red cells has been described.…”

Adhesion molecules and hydroxyurea in the pathophysiology of sickle cell disease

“…21 Zennadi et al demonstrated that ICAM-4 was the red cell ligand for endothelial cell αVβ3 and can be activated by epinephrine through a PKA-dependent pathway, therefore also suggesting a role for physiological stress in triggering vaso-occlusive events. 22,23 In a later study, Kaul et al also demonstrated that inhibition of ICAM-4-αVβ3 interactions by ICAM-4-derived peptides improved circulation of red cells, 24 thereby suggesting that this could be a potentially useful therapeutic target.…”

Intercellular adhesion molecule-4 and CD36 are implicated in the abnormal adhesiveness of sickle cell SAD mouse erythrocytes to endothelium

“…10 The adhesion of SAD RBC to the ICAM-4 peptide (T-8-I)-treated bEnd.3 monolayer was half that recorded on control peptide (A-8-C)-treated endothelium. This difference was maintained, irrespectively of the wall shear stresses applied, and was statistically significant (P<0.001, ANOVA) ( Figure 3A).…”

“…Since the level of PAF in the blood has been reported to be 2-fold higher in patients with sickle cell disease 20 and to enhance sickle cell adhesion in an ex vivo microcirculatory preparation, 10 we investigated SAD RBC adhesion on a PAF-treated bEnd.3 monolayer. We found that PAF significantly increased the adhesion of SAD RBC ( Figure 5A), but not that of wild-type RBC ( Figure 5B).…”

“…Such studies showed that tumor necrosis factor-a (TNFa)-induced retention of SS RBC in the retinal microcirculation could be blocked by an a4β1 antagonist 9 and that platelet activating factor (PAF)-induced adhesion of SS RBC to isolated artificially perfused rat mesocecum vasculature could be blocked by monoclonal antibodies to the vitronectin receptor aVβ3 or by peptides based on the aV-binding domains of ICAM-4. 10,11 Data from approaches looking at the hemodynamic behavior of human RBC flowing in the vascular system of other species may be flawed because of potential interspecies differences in adhesion molecules and receptors. Additionally, most ex vivo studies are performed in plasma-free medium that cannot represent the complexity of the RBC adhesion process in physiological conditions, in which the critical role of plasma proteins (fibronectin, thrombospondin, von Willebrand factor) and leukocytes is well established.…”