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

Bezafibrate mitigates cardiac injury against coronary microembolization by preventing activation of p38 MAPK/NF-κB signaling

Coronary microembolization (CME)-induced inflammatory response and cardiomyocyte apoptosis are the main contributors to CME-associated myocardial dysfunction. Bezafibrate, a peroxisome proliferator-activated receptors (PPARs) agonist, has displayed various benefits in different types of diseases. However, it is unknown whether Bezafibrate possesses a protective effect in myocardial dysfunction against CME. In this study, we aimed to investigate the pharmacological function of Bezafibrate in CME-induced insults in myocardial injury and progressive cardiac dysfunction and explore the underlying mechanism. A CME model was established in rats, and cardiac function was detected. The levels of injury biomarkers in serum including CK-MB, AST, and LDH were determined using commercial kits, and pro-inflammatory mediators including TNF-α and IL-6 were detected using ELISA kits. Our results indicate that Bezafibrate improved cardiac function after CME induction. Bezafibrate reduced the release of myocardial injury indicators such as CK-MB, AST, and LDH in CME rats. We also found that Bezafibrate ameliorated oxidative stress by increasing the levels of the antioxidant GPx and the activity of SOD and reducing the levels of TBARS and the activity of NOX. Bezafibrate inhibited the expression of pro-inflammatory cytokines such as TNF-α and IL-6. Importantly, Bezafibrate was found to mitigate CME-induced myocardial apoptosis by increasing the expression of Bcl-2 and reducing the levels of Bax and cleaved caspase-3. Mechanistically, Bezafibrate could prevent the activation of p38 MAPK/NF-κB signaling. These findings suggest that Bezafibrate may be a candidate therapeutic agent for cardioprotection against CME in clinical applications.

Ubiquinol preserves immune cells in gamma-irradiated rats: Role of autophagy and apoptosis in splenic tissue

Radiation has been applied in cancer treatment to eradicate tumors and displayed great therapeutic benefits for humans. However, it is associated with negative impacts on normal cells, not only cancer cells. Irradiation can trigger cell death through several mechanisms, such as apoptosis, necrosis, and autophagy. This study aimed to investigate the radioprotective efficacy of ubiquinol against radiation-induced splenic tissue injury in animals and the related involved mechanisms. Animals were classified into four groups: group 1 (normal untreated rats) received vehicle 5 % Tween 80; group 2 received 7 Gy γ-radiation; group 3 received 10 mg/Kg oral ubiquinol post-irradiation; and group 4 received 10 mg/Kg oral ubiquinol before and after (pre/post-) irradiation. Ubiquinol restored the spleen histoarchitecture, associated with improved immunohistochemical quantification of B and T lymphocyte markers and ameliorated hematological alterations induced by irradiation. Such effects may be due to an enhanced antioxidant pathway through stimulation of p62, Nrf2, and GSH, associated with reduced Keap1 and MDA. Moreover, ubiquinol decreased mTOR, thus enhanced autophagy markers viz. LC3-II. Furthermore, ubiquinol showed an antiapoptotic effect by enhancing Bcl-2 and reducing caspase-3 and Bax. Consequently, ubiquinol exerts a splenic-protective effect against irradiation via enhancing antioxidant, autophagic, and survival pathways.

Walnut Prevents Cognitive Impairment by Regulating the Synaptic and Mitochondrial Dysfunction via JNK Signaling and Apoptosis Pathway in High-Fat Diet-Induced C57BL/6 Mice

This study was conducted to evaluate the protective effect of Juglans regia (walnut, Gimcheon 1ho cultivar, GC) on high-fat diet (HFD)-induced cognitive dysfunction in C57BL/6 mice. The main physiological compounds of GC were identified as pedunculagin/casuariin isomer, strictinin, tellimagrandin I, ellagic acid-O-pentoside, and ellagic acid were identified using UPLC Q-TOF/MS analysis. To evaluate the neuro-protective effect of GC, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), 2′,7′-dichlorodihydrofluorecein diacetate (DCF-DA) analysis were conducted in H₂O₂ and high glucose-induced neuronal PC12 cells and hippocampal HT22 cells. GC presented significant cell viability and inhibition of reactive oxygen species (ROS) production. GC ameliorated behavioral and memory dysfunction through Y-maze, passive avoidance, and Morris water maze tests. In addition, GC reduced white adipose tissue (WAT), liver fat mass, and serum dyslipidemia. To assess the inhibitory effect of antioxidant system deficit, lipid peroxidation, ferric reducing antioxidant power (FRAP), and advanced glycation end products (AGEs) were conducted. Administration of GC protected the antioxidant damage against HFD-induced diabetic oxidative stress. To estimate the ameliorating effect of GC, acetylcholine (ACh) level, acetylcholinesterase (AChE) activity, and expression of AChE and choline acetyltransferase (ChAT) were conducted, and the supplements of GC suppressed the cholinergic system impairment. Furthermore, GC restored mitochondrial dysfunction by regulating the mitochondrial ROS production and mitochondrial membrane potential (MMP) levels in cerebral tissues. Finally, GC ameliorated cerebral damage by synergically regulating the protein expression of the JNK signaling and apoptosis pathway. These findings suggest that GC could provide a potential functional food source to improve diabetic cognitive deficits and neuronal impairments.

Aloperine: A Potent Modulator of Crucial Biological Mechanisms in Multiple Diseases

Aloperine is an alkaloid found in the seeds and leaves of the medicinal plant Sophora alopecuroides L. It has been used as herbal medicine in China for centuries due to its potent anti-inflammatory, antioxidant, antibacterial, and antiviral properties. Recently, aloperine has been widely investigated for its therapeutic activities. Aloperine is proven to be an effective therapeutic agent against many human pathological conditions, including cancer, viral diseases, and cardiovascular and inflammatory disorders. Aloperine is reported to exert therapeutic effects through triggering various biological processes, including cell cycle arrest, apoptosis, autophagy, suppressing cell migration, and invasion. It has also been found to be associated with the modulation of various signaling pathways in different diseases. In this review, we summarize the most recent knowledge on the modulatory effects of aloperine on various critical biological processes and signaling mechanisms, including the PI3K, Akt, NF-κB, Ras, and Nrf2 pathways. These data demonstrate that aloperine is a promising therapeutic candidate. Being a potent modulator of signaling mechanisms, aloperine can be employed in clinical settings to treat various human disorders in the future.

Sinapic acid ameliorates cardiac dysfunction and cardiomyopathy by modulating NF-κB and Nrf2/HO-1 signaling pathways in streptozocin induced diabetic rats

Hyperglycemia and hyperlipidemia-arbitrated mitochondrial oxidative insult is key reason for cardiac dysfunction and cardiomyopathy. Sinapic acid (SA) is a hydroxycinnamic acid (a polyphenolic acid) present in multiple plants and possesses several pharmacological activities. In this study, we examined the cardio protective effects of SA on streptozotocin (STZ)-induced cardiac insults. STZ and both STZ induced diabetes and normal control rats were administered with 20 and 40 mg/kg SA for 12 weeks. STZ rats demonstrated hyperglycemia and hyperlipidemia. Additionally, STZ administered rats exhibited various histological changes in the cardiac muscles and significantly enhanced CK-MB and LDH. The significant enhancement of oxidative stress, inflammation, and apoptotic markers, and the capacity to curb oxidative stress was significantly abridged in the STZ induced diabetic heart. Chronic treatment with SA (20-40 mg/kg) ameliorated the increased level of glucose, lipid, and cardiac function markers and curtailed histological changes in the cardiac muscles. Chronic treatment also repressed inflammation, oxidative stress and apoptosis thereby and restoring antioxidant defenses in the myocardium of STZ induced diabetic rats. STZ induced cardiac dysfunction and cardiomyopathy by promoting inflammation and oxidative stress. Sinapic acid ameliorates cardiac dysfunction and cardiomyopathy via improvement of hyperglycemia, hyperlipidemia, inflammation, oxidative stress, and apoptosis. Thus, SA possesses possible therapeutic value for the prevention of diabetic cardiac dysfunction and cardiomyopathy via the NRF2/HO-1 and NF-κB pathways.

Puerarin pretreatment attenuates cardiomyocyte apoptosis induced by coronary microembolization in rats by activating the PI3K/Akt/GSK-3β signaling pathway

Coronary microembolization (CME) is associated with cardiomyocyte apoptosis and cardiac dysfunction. Puerarin confers protection against multiple cardiovascular diseases, but its effects and specific mechanisms on CME are not fully known. Hence, our study investigated whether puerarin pretreatment could alleviate cardiomyocyte apoptosis and improve cardiac function following CME. The molecular mechanism associated was also explored. A total of 48 Sprague-Dawley rats were randomly divided into CME, CME + Puerarin (CME + Pue), sham, and sham + Puerarin (sham + Pue) groups (with 12 rats per group). A CME model was established in CME and CME + Pue groups by injecting 42 μm microspheres into the left ventricle of rats. Rats in the CME + Pue and sham + Pue groups were intraperitoneally injected with puerarin at 120 mg/kg daily for 7 days before operation. Cardiac function, myocardial histopathology, and cardiomyocyte apoptosis index were determined via cardiac ultrasound, hematoxylin-eosin (H&E) and hematoxylin-basic fuchsin-picric acid (HBFP) stainings, and TdT-mediated dUTP nick-end labeling (TUNEL) staining, respectively. Western blotting was used to measure protein expression related to the phosphoinositide 3-kinase (PI3K)/protein kinase B (Akt)/glycogen synthase kinase-3β (GSK-3β) pathway. We found that, puerarin significantly ameliorated cardiac dysfunction after CME, attenuated myocardial infarct size, and reduced myocardial apoptotic index. Besides, puerarin inhibited cardiomyocyte apoptosis, as revealed by decreased Bax and cleaved caspase-3, and up-regulated Bcl-2 and PI3K/Akt/GSK-3β pathway related proteins. Collectively, puerarin can inhibit cardiomyocyte apoptosis and thus attenuate myocardial injury caused by CME. Mechanistically, these effects may be achieved through activation of the PI3K/Akt/GSK-3β pathway.

Breviscapine Pretreatment Inhibits Myocardial Inflammation and Apoptosis in Rats After Coronary Microembolization by Activating the PI3K/Akt/GSK-3β Signaling Pathway

Purpose

Coronary microembolization (CME) can cause myocardial inflammation, apoptosis and progressive cardiac dysfunction. On the other hand, breviscapine exerts a significant cardioprotective effect in many cardiac diseases although its role and the potential mechanisms in CME remain unclear. Therefore, the present study aimed to ascertain whether pretreatment with breviscapine could improve CME-induced myocardial injury by alleviating myocardial inflammation and apoptosis. The possible underlying mechanisms were also explored.

Methods

In this study, 48 Sprague-Dawley (SD) rats were randomly assigned to the CME, CME + breviscapine (CME + BE), CME + breviscapine + LY294002 (CME + BE + LY) and sham groups (12 rats per group). In addition, the CME model was successfully established by injecting 42 μm inert plastic microspheres into the left ventricle of rats. Rats in the CME + BE and CME + BE + LY groups received 40 mg/kg/d of breviscapine for 7 days before inducing CME. Moreover, rats in the CME + BE + LY group were intraperitoneally injected with the phosphoinositide 3-kinase (PI3K) specific inhibitor, LY294002 (10 mg/kg) 30 minutes before CME modeling. 12 h after surgery, the study measured cardiac function, the serum levels of markers of myocardial injury, myocardial inflammation-associated mRNAs and proteins, myocardial apoptosis-associated mRNAs and proteins and conducted myocardial histopathology.

Results

The findings demonstrated that pretreatment with breviscapine alleviated myocardial injury following CME by improving cardiac dysfunction, decreasing the serum levels of markers of myocardial injury, reducing the size of myocardial microinfarct and lowering the cardiomyocyte apoptotic index. More importantly, pretreatment with breviscapine resulted to a decrease in the levels of inflammatory and pro-apoptotic mRNAs and proteins in myocardial tissues and there was an increase in the levels of anti-apoptotic mRNAs and proteins. However, these protective effects were eliminated when breviscapine was combined with LY294002.

Conclusion

The findings from this study indicated that breviscapine may inhibit myocardial inflammation and apoptosis by regulating the PI3K/protein kinase B (Akt)/glycogen synthase kinase-3β (GSK-3β) pathway, thereby ameliorating CME-induced cardiac dysfunction and reducing myocardial injury.

Protective effect of glycyrrhizin on coronary microembolization-induced myocardial dysfunction in rats

Coronary microembolization (CME)-induced inflammation and cardiomyocyte apoptosis are two key factors contributing to CME-induced myocardial dysfunction. High-mobility group box-1 (HMGB1) plays essential role in progression of CME-induced injury and inhibition of HMGB1 has been shown to be protective. In present study, the potential effects of glycyrrhizin, a HMGB1 inhibitor, on CME-induced myocardial dysfunction are evaluated. Using a rat model of CME, we administrated glycyrrhizin in rats prior to CME induction. The level of HMGB1, TNF-α, iNOS, IL-6, IL-1β, cleaved caspase-3, Bax, and Bcl-2 were measured. The serum level of cardiac troponin I, creatine kinase, was detected. The cardiac function and cardiomyocyte apoptosis were evaluated. The activation of TLR4/NF-κB signaling pathway was analyzed. Glycyrrhizin prevented CME-induced production of HMGB1, TNF-α, iNOS, IL-6, and IL-1β. Glycyrrhizin inhibited CME-induced cardiomyocyte apoptosis and the expression of cleaved caspase-3 and Bax, while enhanced the expression of Bcl-2. Glycyrrhizin decreased cardiac troponin I and creatine kinase levels and improved cardiac function. Glycyrrhizin prevented the activation of HMGB1/TLR4/NF-κB signaling pathway. Glycyrrhizin ameliorated myocardial dysfunction in CME rats by preventing inflammation and apoptosis of cardiomyocytes.

Nicorandil inhibits cardiomyocyte apoptosis and improves cardiac function by suppressing the HtrA2/XIAP/PARP signaling after coronary microembolization in rats

Cardiomyocyte apoptosis is a key factor in the deterioration of cardiac function after coronary microembolization (CME). Nicorandil (NIC) affects myocardial injury, which may be related to the inhibition of apoptosis. However, the specific mechanism of cardioprotection has not been elucidated. Therefore, we analyzed the impact of NIC on cardiac function in rats subjected to CME and its effect on the high-temperature requirement peptidase 2/X-linked inhibitor of apoptosis protein/poly ADP-ribose polymerase (HtrA2/XIAP/PARP) pathway. Sprague Dawley rats were divided into four groups: Sham, CME, CME + NIC, and CME + UCF. Echocardiography was performed 9 hours after CME. Myocardial injury markers were evaluated in blood samples, and the heart tissue was collected for hematoxylin-eosin staining, hematoxylin basic fuchsin picric acid staining staining, TdT-mediated DUTP nick end labeling (TUNEL) staining, Western blot analysis of the HtrA2/XIAP/PARP pathway, and transmission electron microscopy. NIC ameliorated cardiac dysfunctioncaused by CME and reduced serum levels of CK-MB and LDH. In addition, NIC decreased myocardial microinfarct size and apoptotic index. NIC reduced the Bax/Bcl-2 ratio, levels of cleaved caspase 3/9, cytoplasmic HtrA2, and cleaved PARP, and increased the level of XIAP. The effects of NIC were similar to those of the HtrA2 inhibitor, UCF101. This study demonstrated that NIC reduces CME-induced myocardial injury, reduces mitochondrial damage, and improves myocardial function. The reduction in cardiomyocyte apoptosis by NIC may be mediated by the HtrA2/XIAP/PARP signaling pathway.

miR‑155 modulates high glucose‑induced cardiac fibrosis via the Nrf2/HO‑1 signaling pathway

Cardiac fibrosis is a major pathological manifestation of diabetic cardiomyopathy, which is a leading cause of mortality in patients with diabetes. MicroRNA (miR)‑155 is upregulated in cardiomyocytes in cardiac fibrosis, and the aim of the present study was to investigate if the inhibition of miR‑155 was able to ameliorate cardiac fibrosis by targeting the nuclear factor erythroid‑2‑related factor 2 (Nrf2)/heme oxygenase‑1 (HO‑1) signaling pathway. H9C2 rat cardiomyocytes were cultured with high glucose (HG; 30 mM) to establish an in vitro cardiac fibrosis model that mimicked diabetic conditions; a miR‑155 inhibitor and a miR‑155 mimic were transfected into H9C2 cells. Following HG treatment, H9C2 cells exhibited increased expression levels of miR‑155 and the fibrosis markers collagen I and α‑smooth muscle actin (α‑SMA). In addition, the expression levels of endonuclear Nrf2 and HO‑1 were decreased, but the expression level of cytoplasmic Nrf2 was increased. Moreover, oxidative stress, mitochondrial damage and cell apoptosis were significantly increased, as indicated by elevated reactive oxygen species, malonaldehyde and monomeric JC‑1 expression levels. In addition, superoxide dismutase expression was attenuated and there was an increased expression level of released cytochrome‑c following HG treatment. Furthermore, it was demonstrated that expression levels of Bcl‑2 and uncleaved Poly (ADP‑ribose) polymerase were downregulated, whereas Bax, cleaved caspase‑3 and caspase‑9 were upregulated after HG treatment. However, the miR‑155 inhibitor significantly restored Nrf2 and HO‑1 expression levels, and reduced oxidative stress levels, the extent of mitochondrial damage and the number of cells undergoing apoptosis. Additionally, the miR‑155 inhibitor significantly reversed the expression levels of collagen I and α‑SMA, thus ameliorating fibrosis. Furthermore, the knockdown of Nrf2 reversed the above effects induced by the miR‑155 inhibitor. In conclusion, the miR‑155 inhibitor may ameliorate diabetic cardiac fibrosis by reducing the accumulation of oxidative stress‑related molecules, and preventing mitochondrial damage and cardiomyocyte apoptosis by enhancing the Nrf2/HO‑1 signaling pathway. This mechanism may facilitate the development of novel targets to prevent cardiac fibrosis in patients with diabetes.

Exercise protects against ethanol-induced damage in rat heart and liver through the inhibition of apoptosis and activation of Nrf2/Keap-1/HO-1 pathway

PROPOSE

Understanding the protective effect of exercise against ethanol-induced toxicity through the oxidative stress signaling pathway, apoptosis, and cholesterol metabolism is important to prevent development of cardiovascular diseases.

METHODS

Thirty-two male Wistar rats were randomly divided into four equal groups as follow: control, exercise training (ET), ethanol (4 g/kg of body weight/day) and ET + ethanol. The ET and ET + Ethanol groups ran on the treadmill at 65% maximum running speed for 60 min for five sessions per week for eight weeks. The ethanol and ET + Ethanol groups received ethanol for eight weeks. At the end of the study, animals were anesthetized and blood and tissues were sampled to examine the biochemical and molecular evaluation.

RESULTS

The results showed that the antioxidant enzymes activity decreased and MDA levels increased in the heart and liver of animals in ethanol group compared to control group. The levels of these oxidative biomarkers improved by ET in ET + Ethanol group compared to ethanol group. It showed that ET could protect the heart and liver against oxidative damage induced by ethanol through up-regulating the expression of the Nrf2/Keap-1/HO-1 pathway. ET could exert a cardioprotective effect on ethanol-induced apoptosis through down-regulating the Bax and the caspase-3 and via up-regulating the Bcl-2 expression in the heart. ET could also improve the impairment of cholesterol metabolism induced by ethanol.

CONCLUSION

Exercise can protect against ethanol-induced toxicity through moderating the expression of genes which are involved in oxidative status, apoptosis and cholesterol metabolism.

Aging-regulated anti-apoptotic long non-coding RNA Sarrah augments recovery from acute myocardial infarction

Long non-coding RNAs (lncRNAs) contribute to cardiac (patho)physiology. Aging is the major risk factor for cardiovascular disease with cardiomyocyte apoptosis as one underlying cause. Here, we report the identification of the aging-regulated lncRNA Sarrah (ENSMUST00000140003) that is anti-apoptotic in cardiomyocytes. Importantly, loss of SARRAH (OXCT1-AS1) in human engineered heart tissue results in impaired contractile force development. SARRAH directly binds to the promoters of genes downregulated after SARRAH silencing via RNA-DNA triple helix formation and cardiomyocytes lacking the triple helix forming domain of Sarrah show an increase in apoptosis. One of the direct SARRAH targets is NRF2, and restoration of NRF2 levels after SARRAH silencing partially rescues the reduction in cell viability. Overexpression of Sarrah in mice shows better recovery of cardiac contractile function after AMI compared to control mice. In summary, we identified the anti-apoptotic evolutionary conserved lncRNA Sarrah, which is downregulated by aging, as a regulator of cardiomyocyte survival.

Granulocyte colony-stimulating factor attenuates myocardial remodeling and ventricular arrhythmia susceptibility via the JAK2-STAT3 pathway in a rabbit model of coronary microembolization

Background

Coronary microembolization (CME) has a poor prognosis, with ventricular arrhythmia being the most serious consequence. Understanding the underlying mechanisms could improve its management. We investigated the effects of granulocyte colony-stimulating factor (G-CSF) on connexin-43 (Cx43) expression and ventricular arrhythmia susceptibility after CME.

Methods

Forty male rabbits were randomized into four groups (n = 10 each): Sham, CME, G-CSF, and AG490 (a JAK2 selective inhibitor). Rabbits in the CME, G-CSF, and AG490 groups underwent left anterior descending (LAD) artery catheterization and CME. Animals in the G-CSF and AG490 groups received intraperitoneal injection of G-CSF and G-CSF + AG490, respectively. The ventricular structure was assessed by echocardiography. Ventricular electrical properties were analyzed using cardiac electrophysiology. The myocardial interstitial collagen content and morphologic characteristics were evaluated using Masson and hematoxylin-eosin staining, respectively.

Results

Western blot and immunohistochemistry were employed to analyze the expressions of Cx43, G-CSF receptor (G-CSFR), JAK2, and STAT3. The ventricular effective refractory period (VERP), VERP dispersion, and inducibility and lethality of ventricular tachycardia/fibrillation were lower in the G-CSF than in the CME group (P < 0.01), indicating less severe myocardial damage and arrhythmias. The G-CSF group showed higher phosphorylated-Cx43 expression (P < 0.01 vs. CME). Those G-CSF-induced changes were reversed by A490, indicating the involvement of JAK2. G-CSFR, phosphorylated-JAK2, and phosphorylated-STAT3 protein levels were higher in the G-CSF group than in the AG490 (P < 0.01) and Sham (P < 0.05) groups.

Conclusion

G-CSF might attenuate myocardial remodeling via JAK2-STAT3 signaling and thereby reduce ventricular arrhythmia susceptibility after CME.

Viral-mediated gene delivery of TMBIM6 protects the neonatal brain via disruption of NPR-CYP complex coupled with upregulation of Nrf-2 post-HI

BACKGROUND

Oxidative stress, inflammation, and endoplasmic reticulum (ER) stress play a major role in the pathogenesis of neonatal hypoxic-ischemic (HI) injury. ER stress results in the accumulation of unfolded proteins that trigger the NADPH-P450 reductase (NPR) and the microsomal monooxygenase system which is composed of cytochrome P450 members (CYP) generating reactive oxygen species (ROS) as well as the release of inflammatory cytokines. We explored the role of Bax Inhibitor-1 (BI-1) protein, encoded by the Transmembrane Bax inhibitor Motif Containing 6 (TMBIM6) gene, in protection from ER stress after HI brain injury. BI-1 may attenuate ER stress-induced ROS production and release of inflammatory mediators via (1) disruption of the NPR-CYP complex and (2) upregulation of Nrf-2, a redox-sensitive transcription factor, thus promoting an increase in anti-oxidant enzymes to inhibit ROS production. The main objective of our study is to evaluate BI-1's inhibitory effects on ROS production and inflammation by overexpressing BI-1 in 10-day-old rat pups.

METHODS

Ten-day-old (P10) unsexed Sprague-Dawley rat pups underwent right common carotid artery ligation, followed by 1.5 h of hypoxia. To overexpress BI-1, rat pups were intracerebroventricularly (icv) injected at 48 h pre-HI with the human adenoviral vector-TMBIM6 (Ad-TMBIM6). BI-1 and Nrf-2 silencing were achieved by icv injection at 48 h pre-HI using siRNA to elucidate the potential mechanism. Percent infarcted area, immunofluorescent staining, DHE staining, western blot, and long-term neurobehavior assessments were performed.

RESULTS

Overexpression of BI-1 significantly reduced the percent infarcted area and improved long-term neurobehavioral outcomes. BI-1's mediated protection was observed to be via inhibition of P4502E1, a major contributor to ROS generation and upregulation of pNrf-2 and HO-1, which correlated with a decrease in ROS and inflammatory markers. This effect was reversed when BI-1 or Nrf-2 were inhibited.

CONCLUSIONS

Overexpression of BI-1 increased the production of antioxidant enzymes and attenuated inflammation by destabilizing the complex responsible for ROS production. BI-1's multimodal role in inhibiting P4502E1, together with upregulating Nrf-2, makes it a promising therapeutic target.

Different adaptive NO-dependent Mechanisms in Normal and Hypertensive Conditions

Myocardial infarction (MI) remains the leading cause of death worldwide. We aimed to investigate the effect of NO deficiency on selective biochemical parameters within discreet myocardial zones after experimentally induced MI. To induce MI, the left descending coronary artery was ligated in two groups of 16-week-old WKY rats. In one group, NO production was inhibited by L-NAME (20 mg/kg/day) administration four weeks prior to ligation. Sham operations were performed on both groups as a control. Seven days after MI, we evaluated levels of nitric oxide synthase (NOS) activity, eNOS, iNOS, NFҡB/p65 and Nrf2 in ischemic, injured and non-ischemic zones of the heart. Levels of circulating TNF-α and IL-6 were evaluated in the plasma. MI led to increased NOS activity in all investigated zones of myocardium as well as circulating levels of TNF-α and IL-6. L-NAME treatment decreased NOS activity in the heart of sham operated animals. eNOS expression was increased in the injured zone and this could be a compensatory mechanism that improves the perfusion of the myocardium and cardiac dysfunction. Conversely, iNOS expression increased in the infarcted zone and may contribute to the inflammatory process and irreversible necrotic changes.

miR-30e-5p Mitigates Hypoxia-Induced Apoptosis in Human Stem Cell-Derived Cardiomyocytes by Suppressing Bim

Coronary microembolization can cause slow or no reflow, which is one of the crucial reasons for reverse of clinical advantage from cardiac reperfusion therapy. miRNAs and apoptosis are dramatically involved in the occurrence and process of cardiovascular diseases. Fortunately, human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) have emerged as an appealing model for the evaluation of cardiovascular diseases. Therefore, our study was designed to explore the role of miR-30e-5p and apoptosis in a hypoxia-induced hiPSC-CM injury model. Our results showed that the expression levels of miR-30e-5p were overtly downregulated in a time-dependent manner under hypoxic conditions. Expression of miR-30e-5p was significantly downregulated after 24 hours of hypoxia, hypoxia treatment dramatically induced apoptosis. Calcium handling capability significantly decreased after 24 hours of hypoxia treatment. miR-30e-5p overexpression partially mitigated hypoxia-induced apoptosis and rescued hypoxia-induced calcium handling defects in hiPSC-CMs. The luciferase reporter assay showed that miR-30e-5p can directly target the 3'-UTR of Bim, which is an apoptosis activator and autophagy suppressor. The mRNA and protein of Bim remarkably increased after hypoxia treatment and reduced with miR-30e-5p overexpression. Moreover, downregulation of Bim mitigated hypoxia-induced apoptosis and activated autophagy. These results demonstrated that miR-30e-5p mitigated hypoxia-induced apoptosis in hiPSC-CMs at least in part via Bim suppression and subsequent autophagy activation. Our study suggested miR-30e-5p may act as a potential therapeutic target for coronary microembolization.

Astaxanthin ameliorates cardiomyocyte apoptosis after coronary microembolization by inhibiting oxidative stress via Nrf2/HO-1 pathway in rats

Coronary microembolization (CME) caused by physical obstruction in coronary microcirculation induces myocardial apoptosis and cardiac dysfunction, and it was reported that the inactivation of the Nrf2/HO-1 signaling was involved in this process. Astaxanthin (AST) is a reddish pigment that belongs to keto-carotenoids. It is also a potent antioxidant and has been reported to activate Nrf2/HO-1 signaling in vein endothelial cells. However, it is still unknown whether AST is able to activate Nrf2/HO-1 signaling pathway to protect cardiac functions from CME in vivo. To address this question, rats were orally administrated with AST or AST plus Zinc protoporphyrin IX (ZnPP, a HO-1 inhibitor), followed by CME modeling operation. Then, cardiac function was evaluated by echocardiographic measurement. Myocardial infarction was measured by HBFP staining, and apoptosis was assessed by TUNEL staining. The protein levels and mRNA expressions of Bax and Bcl-2 were measured by Western blot and qRT-PCR, respectively. ELISA was performed to measure the activity of enzymes related to oxidative stress. AST pretreatment dramatically attenuated CME-induced cardiac dysfunction, myocardial infarction, and cardiomyocyte apoptosis. Mechanistically, AST suppressed CME-induced oxidative stress by re-activating Nrf2/HO-1 signaling. HO-1 inhibitor ZnPP completely eliminated the benefits of AST in CEM, supporting the critical role of Nrf2/HO-1 signaling in mediating the cardioprotective function of AST in CME. Conclusion: AST suppresses oxidative stress via activating Nrf2/HO-1 pathway and thus prevents CME-induced cardiomyocyte apoptosis and ameliorates cardiac dysfunction in rats.

microRNA-26a-5p affects myocardial injury induced by coronary microembolization by modulating HMGA1

Coronary microembolization (CME) occurs when atherosclerotic plaque debris is detached during the treatment of acute coronary syndrome with Percutaneous Coronary Intervention (PCI). The complications of distal microvascular embolism, including local myocardial inflammation, are the main causes of myocardial damage and are a strong predictor of poor long-term prognosis and major cardiac adverse events. microRNAs (miRNAs) are involved in the pathophysiological processes of cardiovascular inflammatory diseases. Dysregulation of microRNA (miR)-26a-5p, in particular, is associated with a variety of cardiovascular diseases. However, the role of miR-26a-5p in CME-induced myocardial injury is unclear. In this study, we developed an animal model of CME by injecting microembolic balls into the left ventricle of rats and found that miR-26a-5p expression decreased in myocardial tissue in response. Using a miR-26a-5p mimic, echocardiography, hematoxylin-eosin staining, and Western blot analysis we found that the diminished cardiac function and myocardial inflammation induced by CME is alleviated by miR-26a-5p overexpression. Furthermore, our results show that inhibitors of miR-26a-5p have the opposite effect. In addition, in vitro experiments using real-time PCR, Western blot analysis, and a dual luciferase reporter gene show that HMGA1 is a target gene of miR-26a-5p. Thus, overexpression of miR-26a-5p could be a novel therapy to improve CME-induced myocardial damage.

Modulation of the monocyte/macrophage system in heart failure by targeting heme oxygenase-1

Upon myocardial infarction (MI) immune system becomes activated by extensive necrosis of cardiomyocytes releasing intracellular molecules called damage-associated molecular patterns. Overactive and prolonged immune responses are likely to be responsible for heart failure development and progression in patients surviving the ischemic episode. Heme oxygenase-1 (HO-1) plays a crucial role in heme degradation and in this way releases carbon monoxide, free iron, and biliverdin. This stress-inducible enzyme is induced by various oxidative and inflammatory signals. Consequently, biological actions of HO-1 are not limited to degradation of a toxic heme released from hemoproteins, but also provide an adaptive cellular response against chronic inflammation and oxidative injury. Indeed, the immunomodulatory and anti-inflammatory properties of HO-1 were demonstrated in several experimental studies, as well as in human cases of genetic HO-1 deficiency. HO-1 was shown to suppress the production, myocardial infiltration and inflammatory properties of monocytes and macrophages what resulted in limitation of post-MI cardiac damage. This review specifically addresses the role of HO-1, heme and its degradation products in macrophage biology and post-ischemic cardiac repair. A more complete understanding of these mechanisms is essential to develop new therapeutic approaches.

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

BACKGROUND

Myocardial apoptosis is considered to be the chief cause of progressive cardiac dysfunction induced by coronary microembolization (CME), and the Nrf2/HO-1 signaling pathway is involved in CME-induced myocardial apoptosis. Nicorandil (NIC) has multiple beneficial cardiovascular effects on myocardial injury. Therefore, this study was undertaken to analyze the role of NIC pretreatment in the inhibiting myocardial apoptosis after CME in rats.

METHODS

Forty rats were divided into Sham group, CME group, CME plus NIC (NIC) group, and CME plus AAV9-Nrf2 (AAV9-Nrf2) group (n = 10 per group). CME-induced myocardial apoptosis model was established through injecting plastic microspheres (42 μM) into the left ventricle except the Sham group. NIC group received nicorandil 3 mg/(kg.d) for 7 days before the operation. Cardiac function was assessed by echocardiography. The mRNA expression level of Nrf2 was detected by RT-PCR. The protein expression levels of Nrf2, HO-1, Bcl-2, Bax and cleaved caspase-3 were detected by Western blot. The size of the microinfarction area was measured by HBFP staining; myocardial apoptosis was analyzed by TUNEL staining.

RESULTS

Compared with the sham group, the cardiac function and the expression level of Nrf2, HO-1 and Bcl-2were decreased, while myocardial apoptosis and the expression of Bax and cleaved caspase-3 were increased in the CME group. Compared with the CME group, cardiac function was significantly improved, the expression levels of Nrf2, HO-1, and Bcl-2 were increased, the expression of Bax and cleaved caspase-3 were decreased, and the myocardial apoptosis was attenuated in the NIC group and AAV9-Nrf2 group.

CONCLUSION

NIC pretreatment effectively inhibit CME-induced myocardial apoptosis and improve cardiac function. The protective effects are mediated through the activation of the Nrf2/HO-1 signaling in cardiomyocytes.