A novel VCP modulator, KUS121, attenuates atherosclerosis progression by maintaining intracellular ATP and mitigating ER stress in endothelial cells

Abstract Back ground: Endoplasmic reticulum (ER) stress signaling pathways have pivotal roles in atherosclerosis progression. Recently, we have developed Kyoto University Substance (KUS) 121, which selectively inhibits ATPase activities of valosin-containing protein (VCP) and consequently saves intracellular ATP consumption and mitigates ER stress. KUS121 are known to have protective effects on several disease models including ischemic heart disease and heart failure. However, the efficacy of KUS121 against atherosclerosis was still unclear. Purpose To elucidate the effect of KUS121 on atherosclerosis and its mechanisms. Methods and Results The daily treatment of KUS121 reduced atherosclerosis progression by approximately 40% and macrophage burden in the plaques were also significantly decreased in ApoE knockout mice on high fat diet. Interestingly, we found that C/EBP homologous protein (CHOP), an established ER stress marker, was mainly expressed in plaque endothelium. Therefore, we assessed the action of KUS 121 in endothelial cells using the EA.hy926 cell line. Consequently, it was demonstrated that KUS121 attenuated ER stress-induced apoptosis and downregulated the IRE1α-associated inflammatory pathways. Consistent with these in vitro findings, KUS121 treatment also significantly reduced endothelial apoptosis assessed by TUNEL staining and inflammation examined by immunostaining of NF-κB and ICAM1 in atherosclerotic plaques. Moreover, KUS121 treatment attenuated the recruitment of inflammatory Ly6C high monocytes assessed by bead-labeling technique, which could be due to the reduction of endothelial ICAM1 expression. Furthermore, we also demonstrated that maintenance of intracellular ATP levels mitigates ER stress and prevents pathological states in endothelial cells. Conclusion KUS121 can be a new therapeutic option for atherosclerotic diseases by maintaining intracellular ATP levels and attenuating ER stress-induced apoptosis and inflammation in plaque endothelium.