Hyperglycemia-induced endothelial cell senescence has been widely reported to be involved in the pathogenesis of
type 2 diabetes mellitus‒accelerated
atherosclerosis. Thus, understanding the underlying mechanisms and identifying potential therapeutic targets for endothelial cell senescence are valuable for attenuating
atherosclerosis progression. C1q/
tumor necrosis factor-related
protein 9 (CTRP9), an emerging potential cardiokine, exerts a significant protective effect with respect to
atherosclerosis, particularly in endothelial cells. However, the exact mechanism by which CTRP9 prevents endothelial cells from
hyperglycemia-induced senescence remains unclear. This study aimed to investigate the effects of CTRP9 on
hyperglycemia-induced endothelial cell senescence and
atherosclerotic plaque formation in diabetic
apolipoprotein E knockout (
ApoE KO) mice. Human umbilical vein endothelial cells (HUVECs) were cultured in normal
glucose (5.5 mM) and high
glucose (40 mM) with or without recombinant human CTRP9
protein (3 μg/ml) for 48 h. Purified lentiviruses overexpressing CTRP9 (Lv-CTRP9) and control vectors containing
green fluorescent protein (Lv-GFP) were injected via the tail vein into
streptozotocin-induced diabetic
ApoE KO mice. Results revealed that exposure of HUVECs to HG significantly increased the expression of Krüppel-like factor 4 (KLF4) and
cyclin-dependent kinase inhibitor p21 (p21) and decreased that of
telomerase reverse transcriptase (TERT). Treatment with recombinant human CTRP9
protein protected HUVECs from HG-induced premature senescence and dysfunction. CTRP9 promoted the phosphorylation of
AMP-activated kinase (AMPK), attenuated the expression of KLF4 and p21 induced by HG, and increased the expression of TERT in HUVECs. Furthermore, in the background of AMPKα knockdown or KLF4 activation, the protective effects of CTRP9 were abolished. In-vivo experiments showed that the overexpression of CTRP9 inhibited vascular senescence and reduced
atherosclerotic plaque formation in
ApoE KO mice with diabetes. In conclusion, we demonstrate that KLF4 upregulation plays a crucial role in HG-induced endothelial senescence. This anti-atherosclerotic effect of CTRP9 may be partly attributed to the inhibition of HG-induced endothelial senescence through an AMPKα/KLF4-dependent mechanism, suggesting that CTRP9 could benefit further therapeutic approaches for
type 2 diabetes mellitus‒accelerated
atherosclerosis.