MicroRNA‑21 mediates the protective effects of salidroside against hypoxia/reoxygenation‑induced myocardial oxidative stress and inflammatory response
Bing Liu, Huali Wei, Ming Lan, Na Jia, Junmeng Liu, Meng Zhang
Abstract
Myocardial ischemia‑reperfusion (I/R) injury is the oxidative stress and inflammatory response that occurs when a tissue is reperfused following a prolonged period of ischemic injury. Growing evidence has demonstrated that microRNAs (miRs) are essential in the development of myocardial I/R injury. Salidroside, a phenylpropanoid glycoside isolated from a traditional Chinese medicinal plant, Rhodiola rosea, possesses multiple pharmacological functions and protects against myocardial I/R injury in vitro and in vivo. However, the role of miRs in the cardioprotective effects of salidroside against myocardial I/R injury has not been studied, to the best of our knowledge. In the present study, the role of miR21 in the underlying mechanism of salidroside‑induced protection against oxidative stress and inflammatory injuries in hypoxia/reoxygenation (H/R)‑treated H9c2 cardiomyocytes was determined. The cell viability was assessed with an MTT assay. Lactate dehydrogenase (LDH) release, caspase‑3 activity, malondialdehyde (MDA) level, superoxide dismutase (SOD) and glutathione peroxidase (GSH‑Px) activities were determined by commercial kits. Cell apoptosis was measured by flow cytometry. Intracellular reactive oxygen species (ROS) generation was monitored by DCFH‑DA. The miR‑21 level was quantified by reverse transcription‑quantitative (RT‑q)PCR. The interleukin (IL)‑6, IL‑1β and tumor necrosis factor (TNF)‑α levels were measured by RT‑qPCR and ELISA. The results showed that salidroside pretreatment significantly increased cell viability and decreased the release of LDH, accompanied by an increase in miR‑21 expression in H/R‑treated H9c2 cells and a miR‑21 inhibitor reversed these effects. In addition, the miR‑21 inhibitor also abrogated the inhibition of salidroside on H/R‑induced increases in apoptosis and caspase‑3 activity in H9c2 cells. Salidroside mitigated H/R‑induced oxidative stress as illustrated by the downregulation of ROS generation and MDA level and increased the activities of the antioxidant enzymes, SOD and GSH‑Px, all of which were abrogated in cells transfected with the miR‑21 inhibitor. Salidroside induced a decrease in the expression and levels of the pro‑inflammatory cytokines, IL‑6, IL‑1β and TNF‑α, which were prevented by the miR‑21 inhibitor. Together, these results provide evidence of the beneficial effects of salidroside against myocardial I/R injury by reducing myocardial oxidative stress and inflammation which are enhanced by increasing miR‑21 expression.