L5-induced secretion of Aβ in human platelets. (A-B) Immunoprecipitation isolation and western blot analysis of Aβ secretion in washed human platelets (1.2 × 109/mL) that were incubated with vehicle (0.1% DMSO), L1 (50 μg/mL), L5 (25 or 50 μg/mL), thrombin (0.1 IU), or collagen (1 μg/mL). Platelets were preincubated with vehicle (0.1% DMSO; first column), TS92 (10 μg/mL), or BMS-345541 (25 μM) before treatment with L5 (50 μg/mL). Quantified results are expressed as the mean ± SD (n = 4); P values were determined by using the Student t test. **P < .01, ***P < .001 vs the vehicle-treated control group; ###P < .001 vs the L5-treated group. (C) Western blot analysis showing the activation (phosphorylation) of IKK2 (ie, p-IKK2) by Aβ in the presence or absence of SCH79797, an antagonist of PAR-1 (1 μM). Results are expressed as the mean ± SD (n = 4); P values were determined by using the Student t test. ***P < .001 vs the PBS-treated control group; ###P < .001 vs the Aβ-treated group. (D) A working model for L5-induced Aβ secretion. Black arrow, stimulation; red line with end bar, inhibition; blue arrow, direction or flow. HC, heavy chain of IgG antibody.
