Rationale: Abnormal autophagic death of endothelial cells is detrimental to plaque structure as endothelial loss promotes lesional thrombosis. As emerging functional biomarkers, circular RNAs (circRNAs) are involved in various diseases, including cardiovascular. This study is aimed to determine the role of hsa_circ_0030042 in abnormal endothelial cell autophagy and plaque stability. Methods: circRNA sequencing and quantitative polymerase chain reaction were performed to detect hsa_circ_0030042 expression in coronary heart disease (CHD) and human umbilical vein endothelial cells (HUVECs). Transfection of stubRFP-sensGFP-LC3 adenovirus, flow cytometry, and electron microscopy were used to identify the role of hsa_circ_0030042 in ox-LDL‒induced abnormal autophagy in vitro. Bioinformatic analysis, RNA immunoprecipitation, immunofluorescence assay and other in vitro experiments were performed to elucidate the mechanism underlying hsa_circ_0030042-mediated regulation of autophagy. To evaluate the role of hsa_circ_0030042 in atherosclerotic plaques and endothelial function, we measured the carotid artery tension and performed histopathology and immunohistochemistry analysis. Results: hsa_circ_0030042 was significantly downregulated in CHD, while upon overexpression, it acted as an endogenous eukaryotic initiation factor 4A-III (eIF4A3) sponge to inhibit ox-LDL-induced abnormal autophagy of HUVECs and maintain plaque stability in vivo. Furthermore, hsa_circ_0030042 influenced autophagy by sponging eIF4A3 and blocking its recruitment to beclin1 and forkhead box O1 (FOXO1) mRNA, while hsa_circ_0030042-induced inhibition of beclin1 and FOXO1 was counteracted by eIF4A3 overexpression or decreased hsa_circ_0030042 binding. In high-fat-diet fed ApoE-/- mice, hsa_circ_0030042 also ameliorated plaque stability and counteracted eIF4A3-induced plaque instability. Conclusions: These results demonstrate a novel pathway involving hsa_circ_0030042, eIF4A3, FOXO1, and beclin1; hence, modulating their levels may be a potential therapeutic strategy against CHD.

Diabetic cardiomyopathy, a major cardiac complication, contributes to heart remodelling and heart failure. Our previous study discovered that CCAAT/enhancer‐binding protein β (C/EBPβ), a transcription factor that belongs to a family of basic leucine zipper transcription factors, interacts with the angiotensin‐converting enzyme 2 (ACE2) promoter sequence in other disease models. Here, we aimed to determine the role of C/EBPβ in diabetes and whether ACE2 expression is regulated by C/EBPβ. A type 1 diabetic mouse model was generated by an intraperitoneal injection of streptozotocin. Diabetic mice were injected with a lentivirus expressing either C/EBPβ or sh‐C/EBPβ or treated with valsartan after 12 weeks to observe the effects of C/EBPβ. In vitro, cardiac fibroblasts and cardiomyocytes were treated with high glucose (HG) to investigate the anti‐fibrosis, anti‐apoptosis and regulatory mechanisms of C/EBPβ. C/EBPβ expression was down‐regulated in diabetic mice and HG‐induced cardiac neonatal cells. C/EBPβ overexpression significantly attenuated collagen deposition and cardiomyocyte apoptosis by up‐regulating ACE2 expression. The molecular mechanism involved the binding of C/EBPβ to the ACE2 promoter sequence. Although valsartan, a classic angiotensin receptor blocker, relieved diabetic complications, the up‐regulation of ACE2 expression by C/EBPβ overexpression may exert greater beneficial effects on patients with diabetic cardiomyopathy.

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In advanced atherosclerosis, a large number of necrotic core increases plaque vulnerability, which leads to the occurrence of acute atherothrombotic cardiovascular events. Macrophage apoptosis plays an important role in secondary necrosis. The present study aimed to examine and describe the effect of the traditional Chinese medication Tongxinluo (TXL) on macrophage apoptosis in advanced atherosclerotic plaques and to explore its mechanism. By observing the effect of TXL on ox-LDL-stimulated macrophage apoptosis, it was shown that TXL significantly inhibited ox-LDL-induced apoptosis of macrophages by enhancing autophagy. Therapeutic mechanism of TXL included increasing the expression of Beclin-1 and improving the dissociation of Bcl-2-Beclin-1 Complex. Apolipoprotein E knockout (apoE-/-) mice with a high fat diet were divided into four groups: saline group (Saline gavage), low dose TXL group (0.38 g/kg/d, gavage), medium dose TXL group (0.75 g/kg/day, gavage), and high dose TXL group (1.5 g/kg/day, gavage). 4 weeks after carotid-artery surgery, lentiviral of Beclin-1 silencing was injected through the tail vein. TXL treatment significantly reduced macrophage apoptosis dose-dependently and the result was blocked by Beclin-1 silencing. In addition, the increased Lc3b dots by TXL almost localized to macrophages in advanced atherosclerotic plaque. Compared with the same dose of TXL shBeclin-1 group, plaque area and vulnerability index of TXL groups decreased. The anti-apoptosis effects of TXL on atherosclerosis was related to the improvement of autophagy via Beclin-1.