Sulforaphane attenuates CD36-mediated platelet hyperreactivity through modulating cAMP/PKA/NOX2 signaling in hyperlipidemic conditions

Hyperlipidemia is a risk factor for clinically significant thrombotic events in cardiovascular diseases. Platelet reactivity in hyperlipidemic conditions is enhanced when platelet scavenger receptor CD36 recognizes oxidized lipids in oxidized low-density lipoprotein (ox-LDL) particles, a process that induces atherothrombosis. Sulforaphane (SFN) is a dietary isothiocyanate enriched in cruciferous vegetables and exerts multiple biological activities. The current study sought to investigate the efficacy of SFN on platelet hyperreactivity under hyperlipidemic conditions in vitro and in vivo. Using a series of platelet functional assays in human platelets in vitro, we demonstrated that SFN attenuated ox-LDL-increased platelet aggregation and activation (surface CD62P expression). Mechanistically, studies using pharmacological inhibitors clarified that these inhibitory effects of SFN were mainly modulated by down-regulating CD36-mediated activation of Src kinases, leading to enhanced activation of cyclic adenosine monophosphate/protein kinase A (cAMP/PKA) signaling, and resultant inhibition of NADPH oxidase 2 (NOX2) -dependent generation of reactive oxygen species (ROS). Moreover, 12-week supplementation of SFN-enriched broccoli sprout extract (BSE, 0.06% diet) in hyperlipidemic C57BL/6J mice also decreased platelet hyperreactivity. Studies using pharmacological inhibitors of CD36, protein kinase A (PKA) and NOX2 showed that the efficacy of BSE supplementation was mainly through modulating CD36-mediated the cAMP/PKA/NOX2 signaling. Thus, through modulating the cAMP/PKA/NOX2 pathway and attenuating CD36-mediated platelet hyperreactivity, SFN may play important protective roles in atherothrombosis under hyperlipidemic conditions.