Li-Jiao Xu1, Rong-Chang Chen2, Xiao-Yu Ma3, Yue Zhu3, Gui-Bo Sun4, Xiao-Bo Sun5. 1. School of Life and Environment Sciences, Harbin University of Commerce, Harbin 150076, China.; Institute of Medicinal Plant Development, Chinese Academy of Medical Science, Peking Union Medical College, No. 151, Malianwa North Road, Haidian District, Beijing 100094, China. 2. Institute of Medicinal Plant Development, Chinese Academy of Medical Science, Peking Union Medical College, No. 151, Malianwa North Road, Haidian District, Beijing 100094, China.; Beijing Key Laboratory of Innovative Drug Discovery of Traditional Chinese Medicine (Natural Medicine) and Translational Medicine, Institute of Medicinal Plant Development, Peking Union Medical College and Chinese Academy of Medical Sciences, No. 151, Malianwa North Road, Haidian District, Beijing 100094, China.. Electronic address: chenrongchang456@126.com. 3. School of Life and Environment Sciences, Harbin University of Commerce, Harbin 150076, China. 4. Institute of Medicinal Plant Development, Chinese Academy of Medical Science, Peking Union Medical College, No. 151, Malianwa North Road, Haidian District, Beijing 100094, China.; Zhongguancun Open Laboratory of the Research and Development of Natural Medicine and Health Products, Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences & Peking Union Medical College, No. 151, Malianwa North Road, Haidian District, Beijing 100094, China.. Electronic address: sunguibo@126.com.cn. 5. Institute of Medicinal Plant Development, Chinese Academy of Medical Science, Peking Union Medical College, No. 151, Malianwa North Road, Haidian District, Beijing 100094, China.; Zhongguancun Open Laboratory of the Research and Development of Natural Medicine and Health Products, Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences & Peking Union Medical College, No. 151, Malianwa North Road, Haidian District, Beijing 100094, China.. Electronic address: sunxiaoboyzs@163.com.cn.
Abstract
BACKGROUND: Activation of NLRP3 inflammasome plays a key role in cardiac dysfunction for acute myocardial ischemia-reperfusion injury. Scutellarin (Scu) is a flavonoid purified from Erigeron breviscapus. Whether Scu has any influence on the activation of NLRP3 inflammasome in cardiomyocytes remains unknown. PURPOSE: We aimed to examine the therapeutic effect of Scu on cardiomyocyte ischemia-reperfusion (I/R) injury and its effect on NLRP3 inflammasome in rats with acute myocardial I/R injury and anoxia/reoxygenation (A/R)-induced H9c2 injuries. METHODS: Heart injuries were induced through 30 min of ischemia followed by 24 h of reperfusion. Scu was intraperitoneally administered 15 min before vascular ligation. Effects of Scu on cardiac injury were detected by echocardiograms, TTC staining, and histological and immunohistochemical analyses. The effects of Scu on biochemical parameters were analyzed. H9c2 cells were pretreated with different concentrations of Scu for 6 h before A/R exposure. Afterward, cell viability, LDH release, and Hoechst 33342 and peromide iodine double staining were determined. Western blot analyses of proteins, including those involved in autophagy, NLRP3, mTOR complex 1 (mTORC1), and Akt signaling, were conducted. RESULTS: In vivo study revealed that Scu improved diastolic dysfunction, ameliorated myocardium structure abnormality, inhibited myocyte apoptosis and inflammatory response, and promoted autophagy. Scu reduced NLRP3 inflammasome activation, inhibited mTORC1 activity, and increased Akt phosphorylation. In vitro investigation showed the same results. The Scu-mediated NLRP3 inflammasome and mTORC1 inhibition and cardioprotection were abolished through the genetic silencing of Akt by siRNA. CONCLUSIONS: The cardioprotective effect of Scu was achieved through its anti-inflammatory effect. It suppressed the activation of NLRP3 inflammasome. In addition, inflammasome restriction by Scu was dependent on Akt activation and mTORC1 inhibition.
BACKGROUND: Activation of NLRP3 inflammasome plays a key role in cardiac dysfunction for acute myocardial ischemia-reperfusion injury. Scutellarin (Scu) is a flavonoid purified from Erigeron breviscapus. Whether Scu has any influence on the activation of NLRP3 inflammasome in cardiomyocytes remains unknown. PURPOSE: We aimed to examine the therapeutic effect of Scu on cardiomyocyte ischemia-reperfusion (I/R) injury and its effect on NLRP3 inflammasome in rats with acute myocardial I/R injury and anoxia/reoxygenation (A/R)-induced H9c2 injuries. METHODS: Heart injuries were induced through 30 min of ischemia followed by 24 h of reperfusion. Scu was intraperitoneally administered 15 min before vascular ligation. Effects of Scu on cardiac injury were detected by echocardiograms, TTC staining, and histological and immunohistochemical analyses. The effects of Scu on biochemical parameters were analyzed. H9c2 cells were pretreated with different concentrations of Scu for 6 h before A/R exposure. Afterward, cell viability, LDH release, and Hoechst 33342 and peromide iodine double staining were determined. Western blot analyses of proteins, including those involved in autophagy, NLRP3, mTOR complex 1 (mTORC1), and Akt signaling, were conducted. RESULTS: In vivo study revealed that Scu improved diastolic dysfunction, ameliorated myocardium structure abnormality, inhibited myocyte apoptosis and inflammatory response, and promoted autophagy. Scu reduced NLRP3 inflammasome activation, inhibited mTORC1 activity, and increased Akt phosphorylation. In vitro investigation showed the same results. The Scu-mediated NLRP3 inflammasome and mTORC1 inhibition and cardioprotection were abolished through the genetic silencing of Akt by siRNA. CONCLUSIONS: The cardioprotective effect of Scu was achieved through its anti-inflammatory effect. It suppressed the activation of NLRP3 inflammasome. In addition, inflammasome restriction by Scu was dependent on Akt activation and mTORC1 inhibition.