Open AccessInhibition of platelet adhesion, thrombus formation, and fibrin formation by a potent αIIbβ3 integrin inhibitor from ticks
Author(s) -
Kerkhof Danique L.,
Nagy Magdolna,
Wichapong Kanin,
Brouns Sanne L.N.,
Heemskerk Johan W. M.,
Hackeng Tilman M.,
Dijkgraaf Ingrid
Publication year - 2021
Publication title -
research and practice in thrombosis and haemostasis
Language(s) - English
Resource type - Journals
ISSN - 2475-0379
DOI - 10.1002/rth2.12466
Subject(s) - eptifibatide , platelet , fibrin , chemistry , thrombus , integrin , platelet aggregation inhibitor , pharmacology , fibrinogen , platelet activation , platelet adhesiveness , microbiology and biotechnology , immunology , biochemistry , receptor , medicine , platelet aggregation , biology , myocardial infarction , conventional pci
Background Ticks puncture the skin of their hosts and secrete saliva, containing antiplatelet proteins, into the blood. Here, we studied disagregin, a potent platelet‐inhibiting protein derived from the salivary glands of Ornithodoros moubata , an African soft tick. Whereas conventional αIIbβ3 antagonists contain an Arg‐Gly‐Asp (RGD) sequence for platelet integrin binding, disagregin contains an Arg‐Glu‐Asp (RED) sequence, hypothesizing a different mode of inhibitory action. Objectives We aimed to compare the inhibitory effects of disagregin and its RGD variant (RGD‐disagregin) on platelet activation and to unravel the molecular basis of disagregin‐αIIbβ3 integrin interactions. Methods Disagregin and RGD‐disagregin were synthesized by tert‐butyloxycarbonyl –based solid‐phase peptide synthesis. Effects of both disagregins on platelet aggregation were assessed by light transmission aggregometry in human platelet‐rich plasma. Whole‐blood thrombus formation was investigated by perfusing blood over collagen I with and without tissue factor at a high wall‐shear rate (1000 s −1 ) in the presence of disagregin, RGD‐disagregin, or eptifibatide. Results Disagregin showed inhibition of collagen‐ and ADP‐induced platelet aggregation with half maximal inhibitory concentration values of 64 and 99 nM, respectively. This resembled the complete antiaggregatory effect of eptifibatide. Multiparameter assessment of thrombus formation showed highly suppressed platelet adhesion and aggregate formation with both disagregins, in contrast to eptifibatide treatment, which incompletely blocked aggregation under flow. Fibrin formation under flow was delayed by both disagregin and RGD‐disagregin ( P < .01) and eptifibatide ( P < .05). Conclusions Both αIIbβ3‐blocking disagregins have a strong potential to suppress collagen‐tissue factor–mediated platelet adhesion, thrombus formation, and fibrin formation. Both disagregins can be seen as potential new αIIbβ3 inhibitors.