| Coronary artery atherosclerotic lesions occur and cause vascular stenosis or occlusion, resulting in myocardial ischemia, hypoxia or necrosis. It is caused by heart disease, often called "coronary heart disease." Coronary heart disease is divided into five categories by World Health Organization. There are five kinds of clinical types: silent myocardial ischemia(occult coronary artery disease), angina pectoris, myocardial infarction, ischemic heart failure(ischemic heart disease) and sudden death. It results in a high mortality rate and great harm.Existing researches show that the occurrence and development of coronary heart disease is closely related to a variety of factors,such as high blood pressure, high blood sugar and obesity. Current treatment for coronary heart disease including medication, surgery and thrombolytic therapy. With the establishment and application of artery bypass surgery, thrombolysis, percutaneous transluminal coronary angioplasty and other methods, in most cases, ischemia reperfusion can restore tissue function and structural damage. The patient’s condition can be improved after ischemia reperfusion. But sometimes ischemia reperfusion can’t result in the recovery of myocardial function and promote the myocardial dysfunction and structural damage. In addition, myocardial infarction size is closely related with reperfusion injury. So what is the mechanism of myocardial ischemia-reperfusion injury?Resecent in vitro research has shown that NLRP3 expresses in cardiac microvascular endothelial cells(CMECs) not in cardiomyocytes. Meanwhile SI/R injury can activate NLRP3 inflammasome in CMECs not in cardiomyocytes. Besides SI/R injury can promote the interaction of TXNIP and NLRP3 in CMECs. Si TXNIP can reduce NLRP3 inflammasome activation and SI/R injury in CMECs by measuring the release of LDH and caspase-3 activity. ROS scavenger can promote the separation of NLRP3 and TXNIP in CMECs. ROS plays an great role in MI/R injury. But the function of NLRP3 in MI/R injury hasn’t been reported. In conclusion, we hypothesis that TXNIP mediated NLRP3 inflammasome activation in CMECs and it may provide a novel mechanism in MI/R injury research. The block of TXNIP/NLRP3 signaling pathway can inhibit the activation of NLRP3 inflammasome and provide a new therapy for cure of MI/R injury.NLRP3 is the important component of innate immune. It has been report ed that mitochondrial ROS can promote the separation of TRX and TXNIP and the activation of NLRP3 inflammasome. Meanwhile the ROS scavenger can lead to the inactivation of NLRP3 inflammasome. ROS plays a great role in MIR injury, but the function of NLRP3 in MI/R injury has not been reported.TXNIP can interact with TRX directly and inhibit TRX activity. TXNIP can participate in oxidative stress. It has been reported that the knock down of TXNIP can reduce MIR injury. But the mechanism of how TXNIP is activated is still unknown. We read a lot references and draw a hypothesis. MI/R may result in hugely ROS production, promote the separation of TXNIP and TRX, activation of NLRP3 inflammasome. ASC plays an import role in NLRP3 and Caspase-1. It may influence the inflammatory response and the secretion of IL-1β and IL-18 mediated by NLRP3. How can TXNIP activate NLRP3? And the exact mechanism in MI/R injury is still unknown. Therefore, the research team carried out the following research work.Objectives: To investigate the function and mechanism of NLRP3 inflammasome and TXNIP in mouse myocardial ischemia-reperfusion injury in animal and cell models. Provide a new mechanism for the treatment of myocardial ischemia injury.Methods: The C57 BL / 6 mice were randomly divided into control group, BAY 11-7028(NLRP3 inhibitor) group, TXNIP si RNA group and NLRP3 si RNA group. Half of the mice in each group received myocardial ischemia and reperfusion to construct ischemia-reperfusion(IR) model, and the rest to accept the sham treatment. BAY 11-7028 group received BAY 11-7028 intraperitoneal injection 30 min before surgery.After the successful surgery, mice were scored. And the heart were stained with 2,3,5, a triphenyl tetrazolium chloride and the infarct area were calculated. HE staining to test the pathological changes. TUNEL staining to test the myocardial apoptosis in each group. To detect the myocardial NLRP3 and TXNIP expression by Western Blot. To test the plasma IL-1β and IL-18 levels by ELISA method. To detect the expression of NLRP3 and TXNIP in CMECs and cardiomyocytes by Western Blot. To test the medium IL-1β and IL-18 levels by ELISA method.Results: The myocardial injury is more heavier in IR treatment than the sham-operated mice in each group. There is more myocardial injury in control group than in BAY 11-7028 group. HE and TUNEL staining show that IR treatment result in heavier injury and more cardiomyocyte apoptosis. BAY 11-7028 can reduce the pathological damage caused by IR. The expression of NLRP3 in myocardial is inhibited in BAY 11-7028 group compared with control group. The secretion of IL-1β and IL-18 is reduced in BAY 11-7028 compared with control group. Also there is reduced myocardial damage and increased IL-1β and IL-18 level in TXNIP si RNA group and NLRP3 si RNA group compared with control group(P<0.05). NLRP3 mainly expressed in CMECs. And there is little or no NLRP3 expressed in cardiomyocytes. We observed similar mechanism as animal results in CMECs but not in cardiomycytes. Conclusions: 1. NLRP3 inflammation corpuscles in mouse model of myocardial ischemia-reperfusion in the abnormal activation. 2. Myocardial ischemia-reperfusion injury promotes the hugely release of ROS. Meanwhile MIR results in the abnormal activation of NLRP3 in?ammasome, increased interaction of NLRP3 and TXNIP and enlarged infarction size. 3. Our in vitro result show that NLRP3 mainly expressed in CMECs and barely expressed in cardiomycytes. 4. SI/R results confirmed the interaction of TXNIP and NLRP3 and the activation of NLRP3 in?ammasome in CMECs. |
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