Atherosclerosis remains a major clinical challenge, and although several compounds have been investigated for its treatment, no anti-atherosclerotic drugs have yet been developed that specifically target the hemodynamic forces driving atherogenesis. Previous research from our group has shown that Smad1/5—a signaling molecule activated by both chemical cues such as bone morphogenetic proteins (BMPs) and mechanical stimuli like disturbed blood flow—represents a promising target for this approach.

In this study, we set out to create a high-throughput screening (HTS) platform to identify compounds capable of inhibiting the activation of Smad1/5 induced by both disturbed flow and BMP stimulation, with the ultimate goal of mitigating atherosclerosis. Using a luciferase reporter driven by inhibitor of DNA binding 1 (Id-1), a downstream target of Smad1/5, we screened potential inhibitors in AD-293 cells and found that both KU-55933 and Apicidin effectively suppressed Id-1 expression.

Further experiments demonstrated that treatment of human vascular endothelial cells with 10 μM of either KU-55933 or Apicidin, as well as a combination of half doses of each (referred to as 1/2(K + A)), inhibited the activation of Smad1/5 induced by disturbed flow and BMP4. In terms of functional outcomes, these treatments reduced endothelial cell proliferation by 50.6%, 47.4%, and 73.3% respectively. Notably, while endothelial inflammation was suppressed by KU-55933 and the combination treatment, Apicidin alone did not exhibit this anti-inflammatory effect.

In vivo studies using apolipoprotein E-deficient mice further supported these findings. Administration of KU-55933 and the half-dose combination to these mice inhibited Smad1/5 activation in endothelial cells within athero-susceptible regions, leading to decreased endothelial proliferation and inflammation, and ultimately resulting in the attenuation of atherosclerotic lesions.

Overall, this study presents a novel drug screening platform that successfully identified KU-55933 and its combination with Apicidin as promising therapeutic candidates. By targeting the hemodynamic mechanisms underlying atherosclerosis through the inhibition of Smad1/5 activation, these compounds may offer a new avenue for the development of effective anti-atherosclerotic therapies.