KUS-121

Endoplasmic reticulum (ER) stress pathways contribute to atherosclerosis progression. Recently, we developed Kyoto University Substance (KUS) 121, which selectively inhibits ATPase activities of valosin-containing protein (VCP), consequently conserving intracellular ATP consumption and mitigating ER stress. This study evaluated the efficacy of KUS121 in atherosclerosis.

KUS121 was administered daily to Apoe^-/- mice fed a Western diet (WD) for 8 weeks. KUS121 treatment resulted in a 40-50 % reduction in atherosclerosis progression. Interestingly, we observed that C/EBP homologous protein (Chop), a well-established ER stress marker, was predominantly expressed in plaque endothelium. In human EA.hy926 endothelial cells, KUS121 prevented ER stress-induced apoptosis and downregulated the Inositol-requiring enzyme 1 alpha (IRE1α)-associated inflammatory pathways. Consistent with these in vitro findings, KUS121 treatment significantly reduced endothelial apoptosis, as shown by TUNEL and cleaved caspase-3 staining, and inflammation, as demonstrated by immunostaining of Nuclear factor kappa B (NF-κB) and Intercellular adhesion molecule (Icam) 1 at plaque endothelium. We also demonstrated that KUS121 maintained ATP levels in EA.hy926 cells and atherosclerotic plaque lesions using single-wavelength and the FRET-based fluorescent ATP sensors. Supplementation of intracellular ATP by methyl pyruvate attenuated ER stress-induced apoptotic and inflammatory pathways in endothelial cells, similar to KUS121. Besides affecting ER stress, KUS121 also reduced inflammation even without ER stress by inhibiting glycolysis through increased intracellular ATP levels in LPS-treated EA.hy926 cells.

KUS121 can be a new therapeutic option for atherosclerotic diseases by maintaining intracellular ATP levels, leading to the attenuation of ER stress and glycolysis in plaque endothelium.