Exploring the role and mechanism of hyperoside against cardiomyocyte injury in mice with myocardial infarction based on JAK2/STAT3 signaling pathway.

BACKGROUND: Myocardial infarction (MI) is one of the most deadly diseases in the world. Hyperoside (Hyp) has been shown to have a protective effect on cardiovascular function through various signaling pathways, but whether it can protect myocardial infarction by regulating JAK2/STAT3 signaling pathway is unknown. AIM OF THE STUDY: To investigate whether Hyp could protect the heart against myocardial infarction injury in mice by modulating JAK2/STAT3 signaling pathway and its potential mechanism. METHODS: In vivo experiments, the myocardial infarction model was established by ligating the left anterior descending coronary artery (LAD) of male C57BL/6 mice permanently. The mice were divided into seven groups: sham group, MI group, MI+Hyp (9 mg/kg), MI+Hyp (18 mg/kg) group, MI+Hyp (36 mg/kg) group, MI+Captopril group (15 mg/kg) group and MI+Hyp (36 mg/kg)+AG490 (7.5 mg/kg) group. Each group of animals were given different concentrations of hyperoside, positive control drug or inhibitor of JAK2/STAT3 singaling. After 14 days of administration, the electrocardiogram (ECG), echocardiography and serum myocardial injury markers were examined; Slices of mouse myocardial tissue were assessed for histopathological changes by HE, Masson and Sirius Red staining. TTC and TUNEL staining were used to evaluate the myocardial infarction area and cardiomyocytes apoptosis respectively. The expression of JAK2/STAT3 signaling pathway, apoptosis and autophagy-related proteins were detected by western blot. In vitro experiments, rat H9c2 cardiomyocytes were deprived of oxygen and glucose (OGD) to stimulate myocardial ischemia. The experiment was divided into seven groups: Control group, OGD group, OGD+Hyp (20 µM) group, OGD+Hyp (40 µM) group, OGD+Hyp (80 µM), OGD+Captopril (10 µM) group and OGD+Hyp (80 µM)+AG490 (100 µM) group. Myocardial cell damage and redox index were measured 12 h after OGD treatment. ROS content in cardiomyocytes was detected by immunofluorescence. Cardiomyocytes apoptosis was detected by flow cytometry. The expressions of JAK2/STAT3 signaling pathway-related proteins, apoptosis and autophagy related proteins were detected by western blot. RESULTS: In vivo, hyperoside could ameolirate ECG abnormality, increase cardiac function, reduce myocardial infarction size and significantly reduce myocardial fibrosis level and oxidation level. The experimental results in vitro showed that Hyp could reduce the ROS content in cardiomyocytes, decrease the level of oxidative stress and counteract the apoptosis induced by OGD injury . Both in vivo and in vitro experiments showed that hyperoside could increase phosphorylated JAK2 and STAT3, indicating that hyperoside could play a cardioprotective role by activating JAK2/STAT3 signaling pathway. It was also shown that hyperoside could increase the autophagy level of cardiomyocytes in vivo and in vitro. However the cardiomyocyte-protective effect of Hyp was abolished in combination with JAK2/ STAT3 signaling pathway inhibitor AG490. These results indicated that the protective effect of Hyp on cardiomyocyte injury was at least partially achieved through the activation of the JAK2/STAT3 signaling pathway. CONCLUSION: Hyp can significantly improve cardiac function, ameliorate myocardial hypertrophy and myocardial remodeling in MI mice. The mechanism may be related to improving mitochondrial autophagy of cardiomyocytes to maintain the advantage of autophagy, and blocking apoptosis pathway through phagocytosis, thus suppressing apoptosis level of cardiomyocytes. These effects of Hyp are achieved, at least in part, by activating the JAK2/STAT3 signaling pathway.

The role and mechanism of hyperoside against myocardial infarction in mice by regulating autophagy via NLRP1 inflammation pathway.

ETHNOPHARMACOLOGICAL RELEVANCE: The genus Hypericum are widely distributed in China. Hypericum perforatum L. (genus Hypericum, family Hypericaceae) has a long history as a traditional Chinese medicine, which was traditionally used for the treatment of emotional distress, cardiothoracic depression, and acute mastitis. Hyperoside (Hyp) extracted from Hypericum perforatum L. has been affirmed to exert therapeutic effects on cardiovascular diseases, with widespread existence in plants of genus Hypericum. Hyp could also be extracted from Crataegus pinnatifida Bunge (genus Crataegus pinnatifida Bunge, family Rosaceae), another traditional Chinese medicine that traditionally prevented and treated heart disease in China. The cardioprotection and mechanism of Hyp comprise anti-inflammation, anti-fibrosis, activation of autophagy, and reversal of cardiac remodeling. AIM OF THE STUDY: This study aimed to explore the Hyp effect against MI and its underlying mechanism. MATERIALS AND METHODS: The MI model was constructed in the KM mice via a ligating surgery of the left anterior descending (LAD) coronary artery. Subsequently, the mice were divided into following seven groups: Sham group, MI group, MI + Hyp 9 mg/kg group, MI + Hyp18 mg/kg group, MI + Hyp36 mg/kg group, MI + Fosinopril group, and MI + Hyp-36 mg/kg+3-MA group. Each group was treated with Hyp in different concentrations or positive medicine for two weeks except for the sham group. After two weeks, we examined the cardiac function, electrocardiogram (ECG), myocardial hypertrophy in the non-infarct area, collagen volume fraction (CVF), perivascular collagen area (PVCA) in the infarct area, and several serum cytokines. Autophagy and inflammation in cardiomyocytes were assessed via measuring autophagy-associated proteins and NLRP1 inflammasome pathway related proteins. RESULTS: Hyp reversed LV remodeling and adverse ECG changes through reducing CVF and myocardial hypertrophy. Additionally, Hyp treatment could reduce inflammation levels in cardiomyocytes, compared with those in MI group. Moreover, NLRP1inflammation pathway was activated after MI. Up-regulation of autophagic flux suppressed NLRP1 inflammation pathway after Hyp treatment. However, co-treatment with 3-MA abrogated above effects of Hyp. CONCLUSIONS: Hyp had obvious protective effect on heart injury in MI mice. Echocanrdiographic and histological measurements demonstrated that Hyp treatment improved cardiac function, and ameliorated myocardial hypertrophy and fibrinogen deposition after MI. The partial mechanism is that Hyp could up-regulate autophagy after MI. Furthermore, the promotion of autophagic flux would suppress NLRP1 inflammation pathway induced by MI.