Calorie restriction (CR) reportedly prevents atherosclerotic diseases. Furthermore, CR induces forkhead box protein-O1 (FOXO-1) expression in the skeletal muscle, altering the character of the skeletal muscle. We previously reported that the change in skeletal muscle character, induced by the overexpression of peroxisome proliferator-activated receptor gamma coactivator-1 alpha, suppresses atherosclerotic progression in an atherosclerotic apolipoprotein E-knockout (ApoE-KO) mouse model. Thus, we hypothesized that skeletal muscle alternation induced by FOXO-1 may also have an anti-atherosclerotic effect in ApoE-KO mice. In this study, we investigated whether skeletal muscle-specific FOXO-1 overexpression suppresses the progression of atherosclerosis in ApoE-KO mice. We generated ApoE-KO/FOXO-1 mice, in which an ApoE-KO mouse was crossbred with a mouse presenting skeletal muscle-specific FOXO-1 overexpression (FOXO-1Tg). The mice were sacrificed at 20 weeks of age, and atherosclerotic plaque area and protein expression in the plaque were measured. Additionally, we measured the tumor necrosis factor alpha (TNF alpha)-induced mRNA expression in human umbilical vein endothelial cells (HUVECs), using serum collected from the FOXO-1Tg mice. Accordingly, ApoE-KO/FOXO-1 mice showed a 65% reduced atherosclerotic plaque area when compared with the ApoE-KO mice, with concomitantly reduced vascular cell adhesion molecule-1 (VCAM-1) and macrophage infiltration. As compared to serum from wild-type mice, the serum collected from the FOXO-1Tg mice significantly suppressed the mRNA expression of VCAM-1, an atherosclerosis initiation factor, in TNF alpha-treated HUVECs. Therefore, these data suggest that skeletal muscle-specific FOXO-1 overexpression suppresses the progression of atherosclerosis in ApoE-KO mice. In part, the CR-induced anti-atherosclerotic effect could be attributed to FOXO-1 upregulation in the skeletal muscle. (C) 2021 Elsevier Inc. All rights reserved.