Mechanisms of glabridin inhibition of integrin alpha(IIb)beta(3) inside-out signals and NF-kappa B activation in human platelets

Background Platelets play a crucial role in cardiovascular diseases (CVDs) and are activated by endogenous agonists like collagen. These agonists initiate signal transduction through specific platelet receptors, resulting in platelet aggregation. Glabridin, a prenylated isoflavonoid found in licorice root, is known for its significance in metabolic abnormalities. Glabridin has been observed to inhibit collagen-induced platelet aggregation, but the precise mechanisms, specifically concerning NF-kappa B activation and integrin alpha(IIb)beta(3) signaling, are not yet fully understood. Methods In this study, platelet suspensions were prepared from healthy human blood donors, and the aggregation ability was observed using a lumi-aggregometer. The inhibitory mechanisms of glabridin in human platelets were evaluated through immunoblotting and confocal microscopy. The anti-thrombotic effects of glabridin were assessed by histological analysis of lung sections in acute pulmonary thromboembolism and by examining fluoresceininduced platelet plug formation in mesenteric microvessels in mice. Results Glabridin inhibited integrin alpha(IIb)beta(3) inside-out signals such as Lyn, Fyn, Syk, and integrin beta 3 activation and NF-kappa B-mediated signal events, with similar potency to classical inhibitors BAY11-7082 and Ro106-9920. Glabridin and BAY11-7082 inhibited IKK, I kappa B alpha, and p65 phosphorylation and reversed I.Ba degradation, while Ro106-9920 only reduced p65 phosphorylation and reversed I kappa B alpha degradation. BAY11-7082 reduced Lyn, Fyn, Syk, integrin beta(3), phospholipase C gamma 2 and protein kinase C activation. Glabridin reduced platelet plug formation in mesenteric microvessels and occluded vessels in thromboembolic lungs of mice. Conclusion Our study revealed a new pathway for activating integrin alpha(IIb)beta(3) inside-out signals and NF-kappa B, which contributes to the antiplatelet aggregation effect of glabridin. Glabridin could be a valuable prophylactic or clinical treatment option for CVDs.