Coronary Microembolization Induces Cardiomyocyte Apoptosis in Swine by Activating the LOX-1-Dependent Mitochondrial Pathway and Caspase-8-Dependent Pathway

Tanshinone IIA reduces pyroptosis in rats with coronary microembolization by inhibiting the TLR4/MyD88/NF-κB/NLRP3 pathway

Pyroptosis is an inflammatory form of programmed cell death that is linked with invading intracellular pathogens. Cardiac pyroptosis has a significant role in coronary microembolization (CME), thus causing myocardial injury. Tanshinone IIA (Tan IIA) has powerful cardioprotective effects. Hence, this study aimed to identify the effect of Tan IIA on CME and its underlying mechanism. Forty Sprague–Dawley (SD) rats were randomly grouped into sham, CME, CME + low-dose Tan IIA, and CME + high-dose Tan IIA groups. Except for the sham group, polyethylene microspheres (42 µm) were injected to establish the CME model. The Tan-L and Tan-H groups received intraperitoneal Tan IIA for 7 days before CME. After CME, cardiac function, myocardial histopathology, and serum myocardial injury markers were assessed. The expression of pyroptosis-associated molecules and TLR4/MyD88/NF-κB/NLRP3 cascade was evaluated by qRT-PCR, Western blotting, ELISA, and IHC. Relative to the sham group, CME group's cardiac functions were significantly reduced, with a high level of serum myocardial injury markers, and microinfarct area. Also, the levels of caspase-1 p20, GSDMD-N, IL-18, IL-1β, TLR4, MyD88, p-NF-κB p65, NLRP3, and ASC expression were increased. Relative to the CME group, the Tan-H and Tan-L groups had considerably improved cardiac functions, with a considerably low level of serum myocardial injury markers and microinfarct area. Tan IIA can reduce the levels of pyroptosis-associated mRNA and protein, which may be caused by inhibiting TLR4/MyD88/NF-κB/NLRP3 cascade. In conclusion, Tanshinone IIA can suppress cardiomyocyte pyroptosis probably through modulating the TLR4/MyD88/NF-κB/NLRP3 cascade, lowering cardiac dysfunction, and myocardial damage.

Long non-coding RNA Sox2OT promotes coronary microembolization-induced myocardial injury by mediating pyroptosis

Objective

As a common complication of coronary microembolization (CME), myocardial injury (MI) implies high mortality. Long non‐coding RNAs (lncRNAs) are rarely studied in CME‐induced MI. Herein, this study intended to evaluate the role of lncRNA Sox2 overlapping transcript (Sox2OT) in CME‐induced MI.

Methods

The CME rat models were successfully established by injection of microemboli. Rat cardiac functions and MI were observed by ultrasonic electrocardiogram, HE staining, and HBFP staining. Functional assays were utilized to test the inflammatory responses, oxidative stress, and pyroptosis using reverse transcription quantitative polymerase chain reaction, Western blotting, immunohistochemistry, immunofluorescence, and ELISA. Dual‐luciferase reporter gene assay and RNA immunoprecipitation were conducted to clarify the targeting relations between Sox2OT and microRNA (miRNA)‐23b and between miR‐23b and toll‐like receptor 4 (TLR4).

Results

Rat CME disrupted the cardiac functions and induced inflammatory responses and oxidative stress, and activated the nuclear factor‐kappa B (NF‐κB) pathway and pyroptosis (all P < 0.05). An NF‐κB inhibitor downregulated the NF‐κB pathway, reduced pyroptosis, and relieved cardiomyocyte injury and pyroptosis. Compared with the sham group (1.05 ± 0.32), lncRNA Sox2OT level (4.41 ± 0.67) in the CME group was elevated (P < 0.05). Sox2OT acted as a competitive endogenous RNA (ceRNA) of miR‐23b to regulate TLR4. Silencing of Sox2OT favoured miR‐23b binding to 3′UTR of TLR4 mRNA leading to suppressed TLR4‐mediated NFKB signalling and pyroptosis in myocardial tissues harvested from CME rat models. In addition, miR‐23b overexpression could supplement the cytosolic miR‐23b reserves to target TLR‐4 and partially reverse Sox2OT‐mediated pyroptosis in LPS‐treated H9C2 cells.

Conclusions

This study supported that silencing Sox2OT inhibited CME‐induced MI by eliminating Sox2OT/miR‐23b binding and down‐regulating the TLR4/NF‐κB pathway. This investigation may provide novel insights for the treatment of CME‐induced MI.

Resveratrol Pretreatment Inhibits Myocardial Apoptosis in Rats Following Coronary Microembolization via Inducing the PI3K/Akt/GSK-3β Signaling Cascade

Purpose

Coronary microembolization (CME) is associated with progressive cardiac dysfunction, myocardial inflammation, and apoptosis. Resveratrol (RES) has a considerable role in cardioprotection. However, the contribution and possible mechanisms of RES in CME have not been clearly understood.

Methods

In the current study, 40 SD rats were randomly selected and categorized into various groups including CME, CME + resveratrol (CME + RES), CME + resveratrol+ LY294002 (CME + RES + LY), and sham groups (10 animals in each group). The inert plastic microspheres (42 μm) were injected into the rats’ left ventricle for developing the CME model. Then resveratrol (25 mg/kg/d) was given to the rats in the CME + RES and CME + RES + LY groups for one week before CME induction. Furthermore, LY294002 (10 mg/kg) was intraperitoneally injected into the rats of the CME + RES + LY group 0.5 hours before CME modeling. The cardiac functions, serum levels of myocardial injury biomarkers, myocardial histopathology, and mRNA and proteins associated with myocardial apoptosis were all assessed 12 hours after surgery.

Results

The results revealed that resveratrol pretreatment alleviated the CME-induced myocardial damage by improving cardiac dysfunction, and lowering the serum level of myocardial injury biomarkers, myocardial microinfarct size, and cardiomyocyte apoptotic index. Pretreatment with resveratrol reduced the level of proteins and mRNAs associated with the pro-apoptosis in myocardial tissues and increased the levels of proteins and mRNAs associated with the anti-apoptosis. Moreover, the combined treatment of resveratrol and LY294002 reversed the observed protective effects.

Conclusion

Resveratrol can inhibit cardiomyocyte apoptosis, thus attenuating the CME-induced myocardial injury by triggering the PI3K/Akt/GSK-3β cascade.

Effects of Apigenin on the Expression of LOX-1, Bcl-2, and Bax in Hyperlipidemia Rats

We aimed to investigate the impact of apigenin on LOX-1, Bcl-2, and Bax expression in hyperlipidemia rats and explore the possible molecular pathological mechanism of apigenin in improving hyperlipidemia and preventing atherosclerosis. In hyperlipidemia models, the levels of total cholesterol (TC), triglyceride (TG), low-density lipoprotein cholesterol (LDL-c) and the LOX-1 protein expression were apparently increased (P<0.01), while the high-density lipoprotein cholesterol (HDL-c) levels and the ratio of Bcl-2/Bax were reduced significantly (P<0.01) in comparison with the standard control group. After the treatment of apigenin, the levels of TC, TG, LDL-c, and the LOX-1 protein expression were noticeably decreased (P<0.01), while the levels of HDL-c and the Bcl-2/Bax ratio were increased (P<0.01). The intima was thickened and had protrusions in the hyperlipidemia model group compared to the normal control group. In comparison with the atherosclerosis model group, the degree of aortic lesions in the low-dose, middle-dose, high-dose groups was alleviated. Apigenin can reduce the level of blood lipid, improve hyperlipidemia, and prevent atherosclerosis in hyperlipidemia rats. The molecular mechanism may be related to inhibiting LOX-1 gene expression and increasing the Bcl-2/Bax ratio.

Ligustrazine Attenuates Myocardial Injury Induced by Coronary Microembolization in Rats by Activating the PI3K/Akt Pathway

Background/Aims

Coronary microembolization- (CME-) induced myocardial injury and progressive cardiac dysfunction are mainly caused due to CME-induced myocardial local inflammatory response and myocardial apoptosis. Ligustrazine plays an important protective role in multiple cardiovascular diseases, but its role and the protection mechanism in CME is unclear. This study hypothesized that ligustrazine attenuates CME-induced myocardial injury in rats. This study also explored the mechanism underlying this attenuation.

Methods

Forty SD rats were randomly divided into CME group, ligustrazine group, ligustrazine+LY294002 (ligustrazine+LY) group, and sham group (ten rats in each). In each group, the cardiac function, apoptotic index, serum c-troponin I (cTnI) level, inflammation [interleukin-1β (IL-1β) and tumor necrosis factor-alpha (TNF-α)], and oxidative stress [nitric oxide (NO), superoxide dismutase (SOD), and malondialdehyde (MDA)] were determined. Western blotting was used to detect the proteins which are present in the PI3K/Akt pathway.

Results

Ligustrazine improved cardiac dysfunction induced by CME, increased serum NO and SOD activities, and decreased the serum level in IL-1β, MDA, cTnI, and TNF-α. Moreover, ligustrazine inhibited myocardial apoptosis, which is perhaps caused by the upregulated Bcl-2, the downregulated cleaved caspase-3 and Bax, and the increased protein level in endothelial nitric oxide synthase and phosphorylated Akt. These effects, however, were reduced if ligustrazine was coadministered with LY294002.

Conclusions

Ligustrazine attenuates CME-induced myocardial injury. The effects associated with this attenuation may be achieved by activating the myocardium PI3K/Akt signaling pathway.

Resveratrol Attenuates Cardiomyocyte Apoptosis in Rats Induced by Coronary Microembolization Through SIRT1-Mediated Deacetylation of p53

OBJECTIVE

Coronary microembolization (CME)-induced cardiomyocyte apoptosis is the primary factor in causing cardiac dysfunction. Resveratrol (RES) is known to play a protective role in a variety of cardiovascular diseases, yet it is not known whether RES has a protective role in CME. Therefore, the effect of RES on cardiomyocyte apoptosis and cardiac function damage which are induced by CME in rats was investigated in this study.

METHODS

Fifty Sprague-Dawley rats were separated into 5 groups randomly (10 rats were included in each): sham group, CME group, RES+CME group, RES+CME+Sirtuin-1 (SIRT-1) inhibitor EX527 (RES+CME+EX) group, and CME+EX group. Cardiac function, serum c-troponin I (cTnI) level, apoptotic index, and microinfarct were measured by cardiac ultrasound, myocardial enzyme assessment, TdT-mediated dUTP Nick-end labeling and hematoxylin-basic fuchsin-picric acid staining. The levels of p53, p53 acetylation, SIRT-1, Bax, Bcl-2, and cleaved caspase-3 were detected by Western blot.

RESULTS

Myocardial dysfunction, enhanced apoptotic index as well as cTnI were caused after the operation of CME. Coronary microembolization induced increased expression of p53 acetylation and cleaved caspase-3, while the SIRT-1 and Bcl-2/Bax ratio was reduced. The CME effect was reversed by RES while EX527 attenuated this protective effect.

CONCLUSIONS

Resveratrol can improve cardiac function, in the sense that it attenuates CME-induced cardiomyocyte apoptosis, which is perhaps associated with its inhibition pro-apoptotic pathway of p53 which is transcription-independent.

Association of BAX hypermethylation with coronary heart disease is specific to individuals aged over 70

INTRODUCTION

As a member of B-cell lymphoma-2 (BCL-2) gene family, BCL-2 associated X (BAX) is important for cell apoptosis. In this work, we investigated the association of BAX promoter DNA methylation with coronary heart disease (CHD) in Han Chinese.

METHODS

A SYBR green-based quantitative methylation specific PCR (qMSP) was used to test BAX methylation levels in 959 CHD cases and 514 controls.

RESULTS

Although BAX methylation was not associated with CHD in the total samples, further breakdown analysis by age showed that BAX hypermethylation was significantly associated with CHD for individuals aged over 70 (median percentage of methylation ratio [PMR], 10.70% in cases versus (vs) 2.25% in controls, P =.046). Moreover, BAX methylation was associated with smoking and lipoprotein A (Lp(a)) for individuals aged over 70 (CHD: smoking P = .012, Lp(a) P = .001; non-CHD: smoking P = .051, Lp(a) P = .004). Further analysis of Gene Expression Omnibus (GEO) and The Cancer Genome Atlas (TCGA) data showed BAX expression was upregulated by 5-aza-2'-deoxycytidine demethylation agent (fold = 1.66, P = .038) and inversely correlated with BAX methylation (r = -0.428, P = 8E-05).

CONCLUSIONS

Our study supported that BAX hypermethylation might contribute to CHD risk via downregulation of BAX expression for individuals aged over 70.

Role of metabolic manipulator trimetazidine in limiting percutaneous coronary intervention-induced myocardial injury

BACKGROUND

Trimetazidine (TMZ) is a metabolic modulator that shifts substrate utilization from fatty acid to carbohydrates, thereby, increasing myocardial glucose oxidation and improving myocardial ischemia. We evaluated whether TMZ is effective in reducing myocardial injury after percutaneous coronary intervention (PCI).

METHODS

Patients with stable angina undergoing elective PCI were divided into two groups, one who received oral TMZ (35 mg BD) started 7 days before PCI (n = 48) and second who did not receive any TMZ (in addition to the standard therapy (n = 52)). Troponin-I (cTnI) and creatine kinase-MB (CK-MB) were measured before, 8, and 24 h after PCI. The primary end point was a difference in post-PCI cTnI and CK-MB levels (vs baseline). Frequency of cTnI release in the two groups, total amount of cTnI release, and difference in TIMI flow grade before and after the procedure were also assessed.

RESULTS

Baseline demographics in the groups were comparable. Despite similar baseline levels, post-procedural cTnI was lower at 8 h (0.13 vs 0.56 ng/ml, p = 0.03) and 24 h (0.2 vs 1.13 ng/ml, p = 0.004) in the TMZ group. Decline or no change in cTnI was significantly more common in the TMZ group (26% vs 2%, p < 0.01). Total cTnI released after PCI, as assessed by area under curve was significantly lower in the TMZ group (15.84 vs 3.32 ng h/ml, p = 0.005). Although CK-MB levels were also lower in the TMZ group, the difference was not statistically significant. Incidence of post-PCI TIMI 1 or 2 flow was significantly lesser in the TMZ group.

CONCLUSIONS

Oral TMZ started 7 days before PCI was effective in limiting PCI-induced myocardial injury with lower cTnI levels and higher prevalence of TIMI-3 flow.

The protective effect of activating Nrf2 / HO-1 signaling pathway on cardiomyocyte apoptosis after coronary microembolization in rats

BACKGROUND

Myocardial apoptosis is closely related to myocardial injury caused by coronary microembolization (CME).Nuclear factor erythroid 2-like (Nrf2) has been taken into account as an inhibitor of apoptosis in various tissues. Thus, this research aims to investigate which part Nrf2/HO-1 signaling pathway plays in myocardial apoptosis process following the effect of CME on rats.

METHODS

Separate 40 rats then form them into a group of shame, a group of CME, a group of CME plus AAV-Nrf2(AAV-Nrf2 (CME) group) and a group of CME plus AAV-control (AAV-control (CME) group) stochastically and averagely. Rat CME was established by injecting into the left ventricular chamber, with or without pretreatment of adeno-associated virus Nrf2 (AAV-Nrf2). Echocardiological measurements, using Terminal-deoxynucleoitidyl Transferase Mediated Nick End Labeling (TUNEL) to stain, conducting Quantitative PCR in real time (RT-PCR) as well as Western blotting to evaluate the impacts of them functionally, morphologically and molecularly in CME.

RESULTS

Nrf2 decreased in cardiomyocytes after CME. Upregulation of Nrf2 inside an organism through AAV connect to improving the function of heart as well as attenuating myocardial apoptosis, following the restrain of proapoptotic mRNAs and proteins like caspase-3, caspase-9 and bax expressing as well as the increase of antiapoptotic mRNA and proteins like HO-1 and bcl-2 expressing.

CONCLUSION

Activation of Nrf2/HO-1 pathway can improve CME-induced cardiac dysfunction effectively and also reduce the myocardial apoptosis.

Effects of nicorandil on PI3K/Akt signaling pathway and its anti-apoptotic mechanisms in coronary microembolization in rats

Coronary microembolization (CME) is a common complication of percutaneous coronary intervention (PCI) for acute coronary syndrome. It leads to myocardial apoptosis and cardiac dysfunction. Nicorandil pretreatment can prevent PCI-related myocardial injury and reduce the incidence of no- or slow-reflow phenomena. This cardioprotective effect is probably attributable to the suppression of CME-induced cardiomyocyte apoptosis, but the specific mechanisms have not been clarified. We aimed to investigate the protective effects of nicorandil pretreatment on CME-induced myocardial injury and clarify the underlying mechanisms. In vivo studies, we used echocardiography, cardiac-enzymes measurement, hematoxylin–basic fuchsin–picric acid staining, TUNEL assay, and western blot, and found that CME significantly increased apoptotic cardiomyocytes in the infarct and peri-infarct areas in rats. The PI3K/Akt signaling pathway was involved in cardiomyocyte apoptosis. Nicorandil pretreatment given 7 days before CME effectively reduced cardiomyocyte apoptosis and myocardial injuries in rats, mainly through the activation of PI3K/Akt signaling. In vitro studies further showed that nicorandil reduced hypoxia-induced cardiomyocyte apoptosis and improved cardiomyocyte-survival rate. The PI3K-specific inhibitor LY294002 reduced these cardioprotective effects, indicating that they were attributable to the activation of the PI3K/Akt signaling pathway. In conclusion, nicorandil has significant cardioprotective effects in CME mainly through the activation of the PI3K/Akt signaling pathway and reduction of CME-induced cardiomyocyte apoptosis. Our findings may provide important support for the pre-PCI use of nicorandil to reduce post-PCI myocardial injuries.

Atorvastatin Pretreatment Inhibits Myocardial Inflammation and Apoptosis in Swine After Coronary Microembolization

BACKGROUND/AIM

In addition to its cholesterol-lowering effect, atorvastatin (ATV) has been thought to have multiple cardiovascular benefits, including anti-inflammatory and anti-apoptotic properties. The present study was undertaken to determine whether ATV pretreatment could attenuate myocardial apoptosis and inflammation and improve cardiac function in a swine model of coronary microembolization (CME).

METHODS

Twenty-four swine were randomly and equally divided into a sham-operated (control) group, CME group, and CME plus ATV group. Swine CME was induced by intracoronary injection of inert plastic microspheres (diameter 42 μm) into the left anterior descending coronary, with or without pretreatment of ATV. Echocardiographic measurements, a pathological examination, terminal deoxynucleotidyl transferase-mediated nick end labeling staining, and Western blotting were performed to assess the functional, morphological, and molecular effects in CME.

RESULTS

The expression levels of caspase 3 and tumor necrosis factor-α (TNF-α) were aberrantly upregulated in cardiomyocytes following CME. Downregulation of caspase 3 and TNF-α with ATV pretreatment was associated with improved cardiac function and attenuated serum cardiac troponin I (cTnI) and high-sensitivity C-reactive protein. In addition, through a Pearson correlation analysis, the left ventricular ejection fraction negatively correlated with caspase 3, TNF-α, and cTnI.

CONCLUSION

This study demonstrated that ATV pretreatment could significantly inhibit CME-induced myocardial apoptosis and inflammation and improve cardiac function. The data generated from this study provide a rationale for the development of myocardial apoptosis and inflammation-based therapeutic strategies for CME-induced myocardial injury.