Induction of Autophagy by Tongxinluo Through the MEK/ERK Pathway Protects Human Cardiac Microvascular Endothelial Cells From Hypoxia/Reoxygenation Injury

Abstract

: In contrast to cardiomyocytes, autophagy in cardiac microvascular endothelial cells (CMECs) during ischemia/reperfusion (I/R) injury has not been fully investigated. Tongxinluo (TXL), a traditional Chinese medicine, was shown to be vascular protective. We aimed to elucidate the role of autophagy and its regulatory mechanisms by TXL in CMECs subjected to I/R injury. CMECs were exposed to different treatments for 30 minutes and subjected to hypoxia/reoxygenation each for 2 hours. The results indicated that hypoxia/reoxygenation significantly induced autophagy, as identified by an increased number of monodansylcadaverine-positive CMECs, increased autophagosome formation, and a higher type II/type I of light chain 3 ratio, but not Beclin-1 expression. Autophagy inhibition using 3-methyladenine was proapoptotic, but rapamycin-induced autophagy was antiapoptotic. TXL enhanced autophagy and decreased apoptosis in a dose-dependent manner, reaching its largest effect at 800 μg/mL. 3-methyladenine attenuated the TXL-promoted autophagy and antiapoptotic effects, whereas rapamycin had no additional effects compared with TXL alone. TXL upregulated mitogen-activated protein kinase and extracellular signal-regulated kinase (ERK) phosphorylation; however, PD98059 abrogated ERK phosphorylation and decreased autophagy and increased apoptosis compared with TXL alone. These results suggest that autophagy is a protective mechanism in CMECs subjected to I/R injury and that TXL can promote autophagy through activation of the mitogen-activated protein kinase/ERK pathway.

Protective Effects of MicroRNA-126 on Human Cardiac Microvascular Endothelial Cells Against Hypoxia/Reoxygenation-Induced Injury and Inflammatory Response by Activating PI3K/Akt/eNOS Signaling Pathway

“…As the most common cells in a normal human heart, CMECs play important roles with regard to myocardial protection during reperfusion injury by autocrine or paracrine secretion mechanisms [5]. OverexpressingmiR-126 could enhance ischemic angiogenesis due to stimulating the Akt/ERK–related pathway [20].…”

“…The cardiac microvasculature is located at the terminal end of the circulation, which determines the level of myocardial perfusion and the coronary reserve [3]. Being the most common cells in a normal heart, CMECs are a basic component of the myocardial microcirculation and play a key role in the preservation of cardiomyocytes (CMs) against reperfusion injury [5]. Sustained high levels of deleterious circulatory stimulation are associated with cardiovascular risk factors, including the diabetes-induced responses of vascular endothelial cells (ECs), which lead to a number of cardiovascular and cerebrovascular diseases (CCVD) and endothelial dysfunction [6].…”

Macrophages Aggravate Hypoxia-Induced Cardiac Microvascular Endothelial Cell Injury via Peroxynitrite: Protection by Tongxinluo

“…TXL has satisfactory beneficial effects on cardiovascular disease, particularly in the modulation of microcirculation (Li et al, 2010;ia et al, 2011;Cui et al, 2014). With regard to the mechanism underlying TXL, several researchers have focused on the regulation of eNOS, and still others explore its effect on micro RNAs Wang et al, 2014).…”

Roles of Autophagy in Ischemic Heart Diseases and the Modulatory Effects of Chinese Herbal Medicine

“…Tongxinluo (TXL), a Chinese patented drug consisting of extracts from Radix ginseng, Buthusmartensi, Hirudo etc., has been approved in China to treat cardiovascular and cerebrovascular diseases. Cui et al (2014) …”