Emodin attenuates cardiomyocyte pyroptosis in doxorubicin-induced cardiotoxicity by directly binding to GSDMD.

BACKGROUND: Doxorubicin (Dox), which is an anticancer drug, has significant cardiac toxicity and side effects. Pyroptosis occurs during Dox-induced cardiotoxicity (DIC), and drug inhibition of this process is one therapeutic approach for treating DIC. Previous studies have indicated that emodin can reduce pyroptosis. However, the role of emodin in DIC and its molecular targets remain unknown. HYPOTHESIS/PURPOSE: We aimed to clarify the protective role of emodin in mitigating DIC, as well as the mechanisms underlying this effect. METHODS: The model of DIC was established via the intraperitoneal administration of Dox at a dosage of 5 mg/kg per week for a span of 4 weeks. Emodin at two different doses (10 and 20 mg/kg) or a vehicle was intragastrically administered to the mice once per day throughout the Dox treatment period. Cardiac function, myocardial injury markers, pathological morphology of the heart, level of pyroptosis and mitochondrial function were assessed. Protein microarray, biolayer interferometry and pull-down assays were used to confirm the target of emodin. Moreover, GSDMD-overexpressing plasmids were transfected into GSDMD-/- mice and HL-1 cells to further verify whether emodin suppressed GSDMD activation. RESULTS: Emodin therapy markedly enhanced cardiac function and reduced cardiomyocyte pyroptosis in mice induced by Dox. Mechanistically, emodin binds to GSDMD and inhibits the activation of GSDMD by targeting the Trp415 and Leu290 residues. Moreover, emodin was able to mitigate Dox-induced cardiac dysfunction and myocardial injury in GSDMD-/- mice overexpressing GSDMD, as shown by increased EF and FS, decreased serum levels of CK-MB, LDH and IL-1ß and mitigated cell death and cell morphological disorder. Additionally, emodin treatment significantly reduced GSDMD-N expression and plasma membrane disruption in HL-1 cells overexpressing GSDMD induced by Dox. In addition, emodin reduced mitochondrial damage by alleviating Dox-induced GSDMD perforation in the mitochondrial membrane. CONCLUSION: Emodin has the potential to attenuate DIC by directly binding to GSDMD to inhibit pyroptosis. Emodin may become a promising drug for prevention and treatment of DIC.

Emodin alleviates LPS-induced myocardial injury through inhibition of NLRP3 inflammasome activation.

Myocardial injury and cardiovascular dysfunction are serious consequences of sepsis and contribute to high mortality. Currently, the pathogenesis of myocardial injury in sepsis is still unclear, and therapeutic approaches are limited. In this study, we investigated the protective effect of emodin on septic myocardial injury and the underlying mechanism. Lipopolysaccharide (LPS)-induced C57BL/6 mice and cardiomyocytes were used as models of sepsis in vivo and in vitro, respectively. The results showed that emodin alleviated cardiac dysfunction, myocardial injury and improved survival rate in LPS-induced septic mice. Emodin attenuated the levels of inflammatory cytokines and cardiac inflammation induced by LPS. Emodin reduced NOD-like receptor protein 3 (NLRP3) and Gasdermin D (GSDMD) expression in the heart tissue of LPS-induced septic mice. In vitro, emodin alleviated LPS-induced cell injury and inflammation in cardiomyocytes by inhibiting NLRP3 inflammasome activation. In addition, an NLRP3 inhibitor was used to further confirm the function of the NLRP3 inflammasome in LPS-induced myocardial injury. Taken together, our findings suggest that emodin improves LPS-induced myocardial injury and cardiac dysfunction by alleviating the inflammatory response and cardiomyocyte pyroptosis by inhibiting NLRP3 inflammasome activation, which provides a feasible strategy for preventing and treating myocardial injury in sepsis.

Emodin alleviates myocardial ischemia/reperfusion injury by inhibiting gasdermin D-mediated pyroptosis in cardiomyocytes.

BACKGROUND: Emodin has recently been reported to have a powerful antiinflammatory effect, protecting the myocardium against ischemia/reperfusion (I/R) injury. Pyroptosis is a proinflammatory programmed cell death that is related to many diseases. The present study investigated the effect of emodin on pyroptosis in cardiomyocytes. MATERIALS AND METHODS: Sprague Dawley rats were randomly divided into sham, I/R, and I/R+Emodin groups. I/R model was subjected to 30 minutes' ligation of left anterior descending coronary artery, followed by 2 hours of reperfusion. Cardiomyocytes were exposed to hypoxic conditions for 1 hour and normoxic conditions for 2 hours. The level of the pyroptosis was detected by Western blot, real-time PCR analysis, and ELISA. RESULTS: The level of gasdermin D-N domains was upregulated in cardiomyocytes during I/R or hypoxia/reoxygenation (H/R) treatment. Moreover, emodin increased the rate of cell survival in vitro and decreased the myocardial infarct size in vivo via suppressing the levels of I/R-induced pyroptosis. Additionally, the expression of TLR4, MyD88, phospho-IκBα, phospho-NF-κB, and the NLRP3 inflammasome was significantly upregulated in cardiomyocytes subjected to H/R treatment, while emodin suppressed the expression of these proteins. CONCLUSION: This study confirms that emodin treatment was able to alleviate myocardial I/R injury and inhibit pyroptosis in vivo and in vitro. The inhibitory effect of emodin on pyroptosis was mediated by suppressing the TLR4/MyD88/NF-κB/NLRP3 inflammasome pathway. Therefore, emodin may provide an alternative treatment for myocardial I/R injury.

Association of serum copper, zinc and selenium levels with risk of metabolic syndrome: A nested case-control study of middle-aged and older Chinese adults.

Trace elements, such as copper, zinc and selenium, have been linked to the development of metabolic syndrome. However, previous studies concerning these trace elements in association with metabolic syndrome have presented conflicting results in different countries. The aim of this study was to analyse the association between serum copper, zinc and selenium concentrations and the risk of metabolic syndrome among middle-aged and older Chinese adults. We performed a nested case-control study that included 349 individuals who developed metabolic syndrome (125 males and 224 females) during a 3-year follow-up and 349 controls matched by baseline age (±1 years), sex and area. Serum trace element concentrations were measured using atomic absorption spectrometry. The median serum selenium levels in males and females in the metabolic syndrome group were 82.2 (13.4) µg/L and 82.6 (11.1) µg/L, respectively, which were significantly higher than the serum selenium levels in the control group (p = 0.001 and p < 0.001). After adjusting for potential confounders, the odds ratios of risk for metabolic syndrome in the highest tertile of serum selenium levels were 2.72 [95% confidence interval (CI) 1.43-5.20; p for trend 0.002] for males and 5.30 (95% CI 3.31-8.74; p for trend <0.001) for females, respectively, compared with the lowest tertile. In addition, serum selenium levels were positively correlated with postprandial plasma glucose in both genders (for males: odds ratio 2.42; 95% CI 1.27-4.61; for females: odds ratio 2.11; 95% CI 1.32-3.37) and negatively associated with high-density lipoprotein in only females (odds ratio 3.21; 95% CI 1.75-5.91). These results suggest that higher levels of serum selenium might be an independent risk factor for metabolic syndrome, especially in relation to elevated postprandial plasma glucose and reduced high-density lipoprotein levels. However, we failed to demonstrate an association between copper or zinc status and metabolic syndrome or its components.

Ginsenoside Rb2 promotes glucose metabolism and attenuates fat accumulation via AKT-dependent mechanisms.

Ginsenosides, the major active constituents of ginseng, have been demonstrated possess anti-diabetic, anti-inflammatory effects. Ginsenoside Rb2 (Rb2) is the most abundant saponin in Panax ginseng, this study investigates the role of Rb2 in the anti-hyperglycemic mechanism of insulin-sensitive cell lines 3T3-L1 adipocytes as well as high fat diet-induced obesity mice. Glucose uptake of 3T3-L1 adipocytes was measured. The insulin signaling cascade, including insulin AKT, insulin receptor (IR) beta-subunit, IR substrate (IRS) -1, phosphatidylinositol 3-kinase (PI3K) were also examined. TNF-α-treated 3T3-L1 adipocytes were used as an insulin resistant model in which p-AKT, c-Jun NH2-terminal kinase (JNK), MAPK, and nuclear factor (NF) -κB signaling cascades were examined. As an in vivo study, C57BL/6J mice were fed with a high-fat diet for 9 weeks, with or without Rb2 supplementation. Then we investigated the effects of Rb2 on glycometabolism in these high fat diet-induced obesity mice. Our results demonstrate Rb2 increases glucose uptake in 3T3-L1 adipocytes, independent of insulin receptor ß-subunit (IRß) and principally through the insulin receptor substrate (IRS)-1-phosphatidylinositol 3-kinase (PI3K)-AKT/PKB pathway. Rb2 inhibited TNF-α-induced activation of MAPK and nuclear factor (NF)-κB signaling pathway as well as the expression of inflammatory factors. In high fat diet-induced obesity mice, Rb2 attenuated fat mass and regulated insulin resistance. In mouse adipose tissue, Rb2 phosphorylation of AKT was correlated with glycometabolism. Furthermore, Rb2 attenuates insulin resistance in 3T3-L1 adipocytes, reduces fat mass, and improves insulin sensitivity in high fat diet-obesity mice.