Beta blocker metoprolol protects against contractile dysfunction in rats after coronary microembolization by regulating expression of myocardial inflammatory cytokines

Metoprolol Mitigates Ischemic Heart Remodeling and Fibrosis by Increasing the Expression of AKAP5 in Ischemic Heart

The harm of heart failure mainly causes patients to develop dyspnea, fatigue, fluid retention, and other symptoms, which impair patients' activity tolerance and lead to a dramatic decrease in patients' quality of life. The purpose of this study was to verify whether metoprolol regulates AKAP5 expression and test the role of AKAP5 postinjury in mitigating cardiac infarction-associated tissue remodeling and fibrosis. Sprague-Dawley (SD) rats underwent coronary artery ligation (CAL), which was followed immediately with metoprolol daily. And western blot and coimmunoprecipitation experiments were performed to detect the expression of related proteins in the sham-operated group, model group, and drug-treated group. HW/BW ratio and cardiac expression of COL1 and COL3 were increased in rats following CAL compared with shams. Treatment with metoprolol postinjury was associated with a decrease in HW/BW ratio and COL1/COL3 expression compared to uncontrolled rats. CAL resulted in decreased cardiac AKAP5 expression compared to the control group, while metoprolol treatment restored levels compared to baseline shams. Cardiac expression levels of NFATc3/p-NFATc3 and GATA4 were modest at baseline and increased with injury, whereas metoprolol suppressed gene expression to below injury-associated changes. Immunoprecipitation indicated that AKAP5 could bind and regulate PP2B. In summary, we know that metoprolol alleviates ischemic cardiac remodeling and fibrosis, and the mechanism of alleviating remodeling may improve cardiac AKAP5 expression and AKAP5-PP2B interaction.

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.

Role of TLR4/MyD88/NF-κB signaling pathway in coronary microembolization-induced myocardial injury prevented and treated with nicorandil

Coronary microembolization (CME) is a common complication during the treatment of acute coronary syndrome (ACS) and percutaneous coronary intervention (PCI). Nicorandil can be used to prevent myocardial injury after PCI to reduce the incidence of coronary no-reflow and slow flow, and play a role in myocardial protection, suggesting that its mechanism may be related to the inhibition of CME-induced inflammation of cardiomyocytes. However, the specific mechanism remains unclear. This study investigated the myocardial protective effects of nicorandil pretreatment on CME-induced myocardial injury and the specific mechanism of its inhibition of myocardial inflammation. An CME rat model exhibited CME-induced myocardial inflammation and the elevation of serum tumor necrosis factor-alpha (TNF-α) and interleukin (IL)-1β based on echocardiography, myocardial enzyme detection, hematoxylin and eosin (HE) and hematoxylin-basic fuchsin-picric acid (HBFP) stainings, ELISA, quantitative real-time PCR, and western blotting. Nicorandil treatment seven days before CME induction effectively inhibited myocardial inflammation, ameliorated myocardial injury, and improved cardiac function, mainly by inhibiting Toll-like receptor 4 (TLR4)-mediated myeloid differentiation primary response protein 88 (MyD88)-dependent nuclear factor-kappa B (NF-κB) signaling. Rat neonatal cardiomyocyte experiments further confirmed that nicorandil ameliorated lipopolysaccharide (LPS)-induced myocardial inflammation and improved cardiomyocyte survival. The specific mechanisms mainly involved the inhibition of TLR4/MyD88/NF-κB signaling and the reduction of the inflammatory cytokines TNF-α and IL-1β released from cardiomyocytes. In summary, nicorandil significantly protected cardiomyocytes from CME-induced myocardial injury mainly by inhibiting TLR4/MyD88/NF-κB signaling, thereby reducing the onset of CME-induced myocardial inflammation. This could be one of the important mechanisms for reducing postoperative myocardial injury via PCI-preoperative prophylactic treatment with nicorandil.

Role of high mobility group A1/nuclear factor-kappa B signaling in coronary microembolization-induced myocardial injury

OBJECTIVE

Coronary microembolization (CME) is a common complication in percutaneous coronary intervention (PCI). Local myocardial inflammation caused by CME is the major cause of progressive cardiac dysfunction. High mobility group A1 (HMGA1)/nuclear factor-kappa B (NF-κB) signaling plays an important role in the development and progression of inflammation, but its role in CME remains unclear. This study evaluated the effect of HMGA1/NF-κB signaling on CME-induced myocardial inflammation and cardiac dysfunction.

METHODS

Forty Sprague-Dawley rats were randomly divided into four groups: sham, CME, CME + HMGA1 small interfering RNA (HMGA1 siRNA), and CME + scrambled siRNA (control siRNA) groups, with 10 animals each. The CME model group was established by clamping the ascending aorta and injecting microspheres through the left ventricular apex for embolization, and the sham group was established by injecting the same amount of normal saline. The HMGA1 siRNA group was injected with HMGA1 siRNA transfection complexes into the tail vein 72 h before CME modeling, and the control siRNA group was caudally injected with the same amount of scrambled siRNA 72 h before CME modeling. Twelve hours after the operation, cardiac function, serum c-troponin I level, and microinfarct size were examined. The levels of HMGA1, NF-κB p65, TNF-α, and IL-1β were detected.

RESULTS

Myocardial dysfunction, enhanced serum c-troponin I, and microinfarct were induced following CME. Moreover, CME induced an increased expression of HMGA1, NF-κB p65, TNF-α, and IL-1β. The HMGA1 siRNA reversed these effects by CME, while the scrambled siRNA had no effect.

CONCLUSIONS

HMGA1/NF-κB signaling is involved in CME-induced myocardial inflammation. Inhibition of HMGA1/NF-κB signaling attenuated the CME-induced myocardial injury and improved cardiac function, suggesting a new potential target for the prevention and treatment of CME-induced myocardial injury.

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.

Mechanism of programmed cell death factor 4/nuclear factor-κB signaling pathway in porcine coronary micro-embolization-induced cardiac dysfunction

The aim of this study was to investigate the role of the programmed cell death factor 4 (PDCD4)/nuclear factor-κB (NF-κB) signaling pathway in coronary micro-embolism (CME)-induced inflammatory responses and cardiac dysfunction in a porcine model. Bama miniature pigs were randomly divided into four groups (n = 5 per group). Micro-embolization balls or saline were infused through a microcatheter in the left anterior descending (LAD) artery in the CME and Sham groups, respectively. PDCD4 siRNA or control siRNA mixed with transfection reagent was infused via the LAD artery 72 h before CME induction in the CME + siRNA-PDCD4 and siRNA-control groups, respectively. Cardiac function was evaluated with ultrasound. Tissue biopsy was stained with hematoxylin-eosin (HE) and hematoxylin basic fuchsin picric acid (HBFP) to measure infarction area. Myocardial PDCD4 and tumor necrosis factor-α (TNF-α) mRNA and protein expression were analyzed by quantitative PCR and Western blotting. NF-κB activity was evaluated in gel electrophoretic mobility shift assay. Echocardiographic parameters showed that compared with the sham group, the CME group had impaired heart function, manifested as systolic dysfunction and left ventricular dilatation (reduced left ventricular ejection fraction [LVEF], left ventricular fractional shortening [FS], and cardiac output [CO] [P < 0.05] and increased left ventricular end-diastolic diameter [LVEDd] [P < 0.05]). Compared with the CME group, the CME + siRNA-PDCD4 group had attenuated CME-induced cardiac function damage (increased LVEF, FS and CO [P < 0.05] and reduced LVEDd [P < 0.05]). Compared with the sham group, the CME group had significantly increased PDCD4 and TNF-α mRNA and protein expression and increased NF-κB activity (P < 0.05). These effects were significantly inhibited in the CME + siRNA-PDCD4 group (P < 0.05). In conclusion, PDCD4/NF-κB signaling pathway activation is an important mechanism for CME-induced cardiac dysfunction, suggesting that inhibition of PDCD4/NF-κB signaling pathway may be a potential target for the prevention and treatment of CME.

Effect of metoprolol on myocardial apoptosis after coronary microembolization in rats

BACKGROUND

Coronary microembolization (CME) is a serious complication following percutaneous coronary intervention (PCI) in patients with acute coronary syndromes. The use of metoprolol before PCI can significantly protect ischemic myocardium from myocardial damage, but the function of metoprolol in the treatment of CME is not entirely clear. This study was to explore the effect and significance of metoprolol on myocardial apoptosis and caspase-3 activation after CME in rats.

METHODS

Thirty rats were randomly divided into three groups including sham-operation (control group), CME plus saline (CME group), CME plus metoprolol (metoprolol group), 10 rats for each group. The CME group was induced by injecting 3 000 polyethylene microspheres (42 μm) into the left ventricle during a 10-second occlusion of the ascending aorta; the control group was injected with physiological saline instead of microembolization ball; the metoprolol or saline group was given three intravenous bolus injections before CME. Echocardiography, TUNEL staining, and Western blotting were used to evaluate cardiac function, proportion of apoptotic cells and activation of caspase-3 respectively at 6 hours after operation.

RESULTS

Echocardiographic parameters displayed that the metoprolol group improved cardiac function significantly compared with the CME group (P<0.05). The myocardial apoptotic rate of the CME group as well as the contents of activated caspase-3 increased significantly (P<0.05), both of which were ameliorated significantly by metoprolol treatment (P<0.05).

CONCLUSIONS

This study demonstrates that metoprolol can protect the myocardium during CME in rats by inhibiting apoptosis and improving cardiac function. These results suggest that the inhibition of apoptosis can be a potential therapeutic strategy for the treatment of CME.

Changes in serum and cerebrospinal fluid cytokines in response to non-neurological surgery: an observational study

Background

Surgery launches an inflammatory reaction in the body, as seen through increased peripheral levels of cytokines and cortisol. However, less is known about perioperative inflammatory changes in the central nervous system (CNS).

Our aim was to compare inflammatory markers in serum and cerebrospinal fluid (CSF) before and after surgery and evaluate their association with measures of blood–brain barrier (BBB) integrity.

Methods

Thirty-five patients undergoing knee arthroplastic surgery with spinal anesthesia had CSF and serum samples drawn before, after and on the morning following surgery. Cytokines and albumin in serum and CSF and cortisol in CSF were assessed at all three points.

Results

Cytokines and cortisol were significantly increased in serum and CSF after surgery (Ps <0.01) and CSF increases were greater than in serum. Ten individuals had an increased cytokine response and significantly higher CSF/serum albumin ratios (Ps <0.01), five of whom had albumin ratios in the pathological range (>11.8). Serum and CSF levels of cytokines were unrelated, but there were strong correlations between CSF IL-2, IL-10 and IL-13, and albumin ratios (Ps <0.05) following surgery.

Conclusion

Cytokine increases in the CNS were substantially greater than in serum, indicating that the CNS inflammatory system is activated during peripheral surgery and may be regulated separately from that in the peripheral body. CSF cytokine increase may indicate sensitivity to trauma and is linked to BBB macromolecular permeability.