Background-A diffuse lymphocyte infiltrate is one of the characteristic features of ulcerative colitis (UC). Such lymphocyte recruitment requires lymphocyte rolling mediated by L-selectin ligand carbohydrates (6-sulfo sialyl Lewis X-capped O-glycans) and/or mucosal addressin cell adhesion molecule 1 (MAdCAM-1) expressed on high endothelial venule (HEV)-like vessels. The present study was undertaken to elucidate the role of MAdCAM-1 posttranslationally modified ("decorated") with L-selectin ligand carbohydrates in UC pathogenesis and consequent clinical outcomes.

1 A murine anti-human vWF monoclonal antibody, AJvW-2, was developed that inhibited the interaction between platelet glycoprotein Ib (GPIb) and von Willebrand factor (vWF) during the ristocetin-(IC 50 =0.7+0.1 mg ml 71 ) and botrocetin-(IC 50 =1.8+0.3 mg ml 71 ) induced aggregation of human platelets. 2 AJvW-2 inhibited the high shear stress (10.8 N m 72 ) induced aggregation of human platelets dosedependently with an IC 50 =2.4+0.3 mg ml 71 , but had no e ect on low shear stress induced platelet aggregation (1.2 N m 72 ) up to 100 mg ml 71 . 3 AJvW-2 also inhibited the high shear stress (5.0 N m 72 ) induced adhesion of human platelets to collagen I with the same e cacy (IC 50 =2.4+0.3 mg ml 71 ), but had no e ect at low shear conditions (1.5 N m 72 ). 4 AJvW-2 inhibited the botrocetin-induced aggregation of platelets from guinea-pig, rat, rabbit, dog and pig at the same concentration range as human platelets; it likewise also inhibited the high shear stress induced aggregation and adhesion to collagen I of guinea-pig platelets. 5 AJvW-2 prevented arterial thrombus formation in guinea-pigs at a dose of 100 mg kg 71 without prolonging the template bleeding time, whereas the GPIIb/IIIa antagonist lami®ban mediated inhibition of thrombosis at 1000 mg kg 71 was accompanied by a signi®cant prolongation of the bleeding time. 6 These results suggest that AJvW-2 is a potent inhibitor of the GPIb-vWF interaction and a potential novel antithrombotic agent with lower bleeding risk than GPIIb/IIIa antagonists.

The interaction between platelet glycoprotein Ib and von Willebrand factor (vWF) plays a crucial role in platelet-mediated thrombus formation under high-shear-stress conditions. The aim of this study was to investigate the antiplatelet profile of a humanized anti-vWF monoclonal antibody, AJW200. In vitro studies were performed with a modified cone-and-plate viscometer and human platelets. AJW200 inhibited high-shear-stress-induced platelet adhesion, aggregation, and thrombin generation, but it did not have such effects under low-shear-stress conditions. Although abciximab inhibited platelet aggregation under both shear stress conditions, it did not inhibit platelet adhesion and thrombin generation. In addition, the pharmacokinetics and pharmacodynamics of AJW200 were evaluated in cynomolgus monkeys. Sustained inhibition of ristocetin-induced platelet aggregation was observed over 24 hours, 6 days, and 2 weeks after a single bolus injection of 0.3, 1, and 3 mg/kg, respectively. Moderate prolongation of the bleeding time was observed at the doses of 1 and 3 mg/kg. Abciximab markedly prolonged the bleeding time at 0.4 mg/kg, at which concentration complete inhibition of ADP-induced platelet aggregation was observed. These results suggest that glycoprotein Ib-vWF blockade with AJW200 results in a sustained antiplatelet effect without extensive prolongation of the bleeding time, probably due to a shear-stress-dependent inhibitory action.

Oral treatment with the selective small molecule α4 integrin antagonist (AJM300) prevented the development of colitis and its efficacy was comparable to that of the anti-α4 integrin antibody.